I know that external USB devices can be added and removed while the power is on, but does this apply to the internal USB ports on the mobo? I've got an internal card reader that isn't recognized in My Computer. In fact, my PC usually won't recognize any USB devices unless I plug them in while the the power is on. So is it safe to connect the reader to the mobo's internal "USB pins" while the power is on? Or will I short something out and cause a mess? Thanks.

"...my PC usually won't recognize any USB devices unless I plug them in while the the power is on." That is not normal. Windows must have the proper info about the mboard USB hardware in order for it and detection of USB devices to work properly. Even XP doesn't always get that right on its own. Load the chipset drivers including those for USB for your mboard. You should always do that after anytime you have run Windows Setup from scratch. "So is it safe to connect the reader to the mobo's internal "USB pins" while the power is on? " Yes, but be careful you only touch the right pins. You shouldn't have to do that when the computer is on if your USB support is working properly. Any USB port is hot swappable and it will not hurt anything. Just make sure you connect to the proper pins - their arrangement was never standardized - there are several possible common arrangements, plus some oddballs. If your reader does not have individual connectors on each wire, make sure the connector it has is compatible with the mboard pin arrangement.

When I try to reinstall the USB 2.0 drivers from the mobo CD, I get a message that's something like this: "You're using Windows XP SP1 or higher. USB 2.0 drivers are already installed."

That's not what I meant. If you have XP SP1 or SP2, it has USB 2.0 support built in and driver support for it will automatically be installed. The original XP without SP1 or SP2 does not support USB 2.0, but you can upgrade the original XP to SP1 or SP2 in order to support it. I'm talking of the chipset drivers for the main chipset on the mboard, which has USB hardware support built into it. If XP is not recognizing USB devices that are already plugged in before the computer is booted, it is probably the case that your main chipset drivers have not been loaded since the last time Windows Setup was run. Xp does not necessarily load all the right driver support for the main chipset on it's own. E.g. if you have a Via chipset, you load the Hyperion 4 in 1 drivers which include the USB drivers. If your USB is not working properly, the proper USB hardware drivers have probably not been loaded; if they have not been loaded it is probably the case the main chipset drivers have not been loaded either. Therefore, you should load all the main chipset drivers, not just those for USB.

All of the nForce/Raid/USB/LAN have been installed. The computer still needs to be powered on to recognize the USB devices.

"All of the nForce/Raid/USB/LAN have been installed." Is nForce the main chipset? Lan drivers have nothing to do with this problem. Did you actually re-load the drivers? If you did not re-load the drivers and you are looking at what is in Device Manager, it may seem everything has been installed. You could check settings in your bios Setup, but I don't think I've ever seen a setting that would disable the detection of USB devices that were already plugged in when the system is off. You could try enabling legacy USB support (or USB keyboard, USB mouse support) in the bios but I doubt it would help. You could try setting the bios to defaults (after making note of any custom settings you have made) but I doubt it would help. The only other thing I can think of is your Windows installation has corrupted or missing essential Windows files required to make the USB work properly. In that case, try an XP Repair Setup. An XP Repair Setup will not harm your existing Windows installation, but it can only fix things Windows detects as wrong, and/or replace corrupted or missing Windows files that are on your original XP CD. If running it doesn't cure enough of your problems and/or the problems are caused by things not on the original Windows CD, you will probably have to make a clean install of Windows from scratch. You will need a Windows CD of the same version as the one of your Windows installation, and the Product Key, preferably the one that was used to install it, but it can be one for the same version as the one of your Windows installation. how to do an XP Repair Setup, step by step: http://www.windowsreinstall.com/winxppro/installxpcdrepair/indexfullpage.htm If you have a brand name system, it may have come with only a Recovery CD instead of a Windows CD. Some Recovery CD's are actually Windows CD's with added stuff that allows you to access the hidden partition and restore your original software - that type can be often be used the same way as a Windows CD.

XP MCE is the same as XP Pro with a handful of Pro features that most people don't use excluded, plus added MCE only related stuff, mostly for extra multimedia and MCE compatible device support. If you have two XP MCE OEM CDs, the XP Repair setup procedure is the essentially the same as what you see at the above link except that you will be using the first CD, then be asked to insert the second CD to install MCE only stuff, then be asked to insert the first CD again. If your XP MCE was preinstalled and you have only a Recovery CD, or you can make one or more in Windows, I don't know if you can do the XP Repair Setup without borrowing someone elses two XP MCE OEM CDs - some custom builders supply those CDs when they make an XP MCE syatem, or if you are resourceful you can get them yourself if you meet the qualifications.