|That's a no brainer question.|
On the emachines web site.
Or - you can search for possibly newer drivers for the specific Intel main chipset and it's built in video on the Intel web site, and the specific Realtek audio chip on the Realtek web site.
The drivers for USB 1.x (USB 1.0 or USB 1.1) support are generic drivers that are built into the operating system - they're auto installed when you install the operating system, in Win 98 and up.
XP must have SP1 or later updates integrated into it in order to be able to provide built in generic USB 2.0 support
That USB 2.0 support is only enabled and the generic drivers installed for it AFTER the main chipset drivers for the mboard have been installed, which include info the operating system needs to be informed of about how the main chipset supports USB 2.0 and what type it is.
XP doesn't have the drivers built in for most things that first came out after XP was first released, circa 2001, and it doesn't have some of the drivers built in for things made before that.
Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, USB 2.0 if it has it, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them.
The emachines web site has the Intel main chipset drivers too.