hey man, check out this page... Listed are a bunch of different oc programs you can check out...
it'd help if I posted a link eh?
IMO, I dunno what kinds of games you play, but I really don't think oc your system is going to get you anywhere at all. As you said you'll get better cooling if you can overclock.. why not look into a newer video card?
I found an MSI 9200SE for 40 bucks
9600SE for 105
9600Pro for 135
9600XT for 145
If you were gonna spend money to get a hsf for you cpu (20) and something for your video card (10-20) might wanna look into a 9200SE... wouldn't get you much further, but it'd be better than the TNT2.