compaq Desktop pc info required

i have aquired (legally) a desktop pc from a college due to upgrades. It has
a celeron 600mhz processor and a 10 gig hd. I can not find any model numbers
as such on the case but it does have a sticker with the following:
ENS/C600/10e/8/64

I assume that c600 is the model number?
My question is, what is the biggest hard disk this system will support, the
fastest processor and the max ram ( has 3 slots and system shows as a total
of 192 so prob got 3 sticks of 64) it will support? had a look on compaq
site but can find nothing using the ENS tag from above...
Also does anyone have a pdf manual for the hardware?

Cheers
harvy