Use Riva Tuner or Ati Tool.......OC and then start Riva Tuner's Hardware monitoring tool and run a game like NFS Carbon for about 2hrs and check the temps.....or just do it by hitting Scan For Artifacts in ATi Tool....
Don't go for Auto...it just goes high on mem and low on core.....and in some lowend cards the mem is not cooled and may get screwed up...
@codename_romeo: Don't try to OC coz it may just help by 2-3fps and in most mobos the IGP is built into the main chipset or nothbridge..so you may end with your mobo screwed...