I can overclock my ATi Radeon 7500:

Core @ 333mhz
mam @ 290mhz (I pray for it doesn't burn my Video Card to run 3Dmark 2001)~_~

However, it don't give me much more marks, it is around 3500.(original setting is around 3450)

I have a Pentinum !!! 866 o/c 1046mhz
128M pc-133
Asus cusl2 motherboard
One Network Card installed
A cmi8738 Sound card (forgot the brand) 5.1 suround sound support
17" ATX Case (of couse) ^.^
...... something like that

How Fast you can do?