It Is a AMD Duron Processor, currently 224 Mb ram and 1.67GB hard drive space. Most of that can be freed as all that is needed on the computer is the printer, microsoft office, real one, an anti-virus and the internet.
Your HDD will let you down, not nearly big enough for anything, the rest is fine.
Buy a new HDD on Ebay, you can get a 6Gb one for less than £10 including postage although I'd go for at least 40Gb.
It's held in by 4 screws and has 2 plugs, takes around 10 minutes to change, just remember that the red stripe on the data cable goes next to the power plug and make sure the jumper on the new HDD is set to Master.