|If your downloads that are taking up too much space are mostly not programs - e.g. music, movies, etc., or games you're not presently using, copy most of the xxxx things to CDs or DVDs, and when you're sure they work, delete the ones you have copies of ! Many people have so much of that stuff on their hard drives it would take as long as years to listen to or watch all of them !|
Run them from the disks, or copy them to the hard drive as needed, and when you're finished with them (e.g. do you watch movies over and over again in a short time - most people don't), delete the ones off your hard drive that you have copies of !
Or - get yourself an external drive to copy most of that kind of thing to, delete the originals from the hard drive !
Where are F and G?
If either is an external drive, copy stuff like mentioned above to an external drive, delete the originals on C !
Or for that matter, you can install most programs on other than the C drive !
If you have one only hard drive and neither of those is an external drive....
If you have only one hard drive, and if it still has it's original brand name system software installation on it, the hard drive came with at least two partitions, sometimes three, on it. They are small - only a little more than big enough to hold the data the brand name installed on them. Depending on your system, the data in at least one of those may that on a Recovery partition - it may contain data essential to restoring the original data on the C partition, if you need to. If you have a set of Recovery disks that can restore the contents of C without needing the data the brand name installed on another partition on the original drive, either that was supplied with the new computer, or that you made in Windows by using a program supplied by the brand name, then you could delete the two small partitions and use their space, and still have the option of resoring the original brand name software installation.
However, you can't add the un-allocated space made available when you delete the small partitions to the C partition in XP itself, unless you delete the C partition too, and install Windows from scratch from a regular CD or the equivalent.
You CAN add the space the small partitions were using, if you use a third party program such as Partition Magic 8.x (you have to pay for it) or another freeware or paid "partition manipulation" program (e.g. Partiton Logic is similar to Partition Magic and it's free, but last time I checked it's not Vista / Windows 7 compatible yet - neither is PM 8.x for that matter).
Or - just get and install a larger hard drive - you can copy the contents of the existing drive with free software, when the bigger drive is in an external drive enclosure, then swap drives.
The hard drive manufactures usually have free software you can do that with, but you can only use it if at least one of the drives is their brand. E.g. if one or both is Seagate, the current MaxBlast is an OEM (somewhat crippled) version of Acronis software - you can copy the entire original drive's data and all partitions on it, but not individual partitions, to the new drive. (If you don't want the partitions other than the one C was on, delete them BEFORE you run the software.)
See Response 9 in this recent Topic for more info, or response 5 if you want to install Windows from scratch on a bigger hard drive: