If you get lucky, a non-TC AGP 6200 can unlock the second quad, turning it into a 6600.
Or you could skip lunch or mow another lawn and cough up for a 6600 non-gt in the first place. I don't think the price difference between a $50 9550/6200 and a $70 6600 warrants the lower performing tech if you're interested in playing any game, ever. Hell, $80 for an X800GT or $100 for a 6600GT/X1600/6800XT is well worth it in comparison.
I know the extra $50 seems like a pile of cash, but the gaming experience on the absolute bottom of the barrel hardware just isn't worth the price of admission. Does 800x600 with low quality textures and all the eye candy off with occasional dips into single digit frame rates on modern games sound good to you? Because that's what you get with a 9600 Pro level card today (aka X300SE, X600). On-board video (X200, 6150) isn't that far behind.
Unless you're mostly playing Directx 7 games from 2001, in which case definitely go for a ti4200 from the geeks for $33. It'll be performance comprable to a 9600 Pro or overclocked 9550, but save you another 10 bucks.