The simple answer is to back up your files and then reset it to factory and then put the files back on it and reinstall the programs that you need.

you will get an HUGE improvement if you replace its internal hard drive with a solid state disk (SSD).

I installed a Trascend 64 Gigabyte SSD disk on mine and I can tell you that, with a fresh install of windows XP, it boots in less than 6 seconds.

Anyway you will see a good improvement (that does not require you to reinstall the whole operating system) you can upgrade its ram to 2 Gigabytes. (it is the maximum supported: you can't go beyond this limit with this pc)

Try it. you won't be disappointed at all.