geforce and overheating

[Davin]

yo people
I'm not much of a computer fixery person, so i thought id ask here
question 1:
comp specs:
512 ram
1.5 ghz processor
geforce4 64 mb video ram
I think thats everything important
oh and DSL internet connection (don't know much more about it than that)
If all/most of the graphics settings are set on medium, will my comp be able to handle ps with no lockups/freezes
three-four second lag i can handle but i don't want to be
i'll probably be playing on markov
constantly restarting my comp
question 2:
haven't gotten ps yet
in many of the other graphics intensive games i play (sport/flight sims usually), the screen would lose some texture in areas or portions of the screen would go dark, freezing the comp. The sound would continue fine though
so far i've tracked that to overheating, and have been running a fan (big fan, as in the type you cool your room with on a hot day) and a smaller, comp-specific fan you plug into the back of the comp. without the larger fan, it still freezes and locks up. i'd like to remove the big fan for obvious hazard reasons...
if theres something obvious i overlooked, etc. remember, i'm not a computery person
any suggestions?