You omitted some important details. eMachines never shipped this desktop with Windows XP installed, hence they offer no support for it in that OS.
Your best bet is to determine which Intel VGA chipset it uses then check that chipset makers website for compatible drivers.
Or you can try running Everest on it to see if it will find a driver for you: (or at minimum, determine what the Intel chipset number is).
To find make and model of pc hardware, EVEREST Home Edition
is a free system diagnostics, system information program that will id most hardware onboard a mb. as well as the actual motherboard. It will, in some cases, actually provide a download link for the driver.
Alternate Everest download link: (offers 2 sites to dl program from)
Run the program and then:
Click on Computer
Click on Summary
Right hand window (hardware) if the text is BLUE
this is a link to the web site for that particular hardware.
If you have additional questions or need further help, please post a "copy and paste" of the COMPUTER SUMMARY report (Leave out the Debug–PCI section) from Everest.
The other alternative is to search the eMachines website for older models having the same VGA chip and has support in Windows XP.
And a last method is to reinstall Vista on it and open Device Manager and take note of the hardware list. Something that should have been done before removing Vista.