best small(ish) gpu to go into a micro atx case?

[squarehead94]

hey all, so after building my dads xmas pressie, hes given me his old rig. this will be my main rig (going against building a new one with top spec, i get a load of money in august, rather wait til i can afford a monster pc)
so currently its low spec. its in a cube case, with temp reader and stuff. coolings ok but not awesome. it currently runs a pentium d 3.4ghz but im seeing what the mobo can take max cpu wise, gonna go e8400 or q6600 because there cheap. but not yet, cpu wise im happy at the mo, what i need is a gpu, currently using a donated radeon x1900 (dad took his 8800 gtx to put in his new rig, til he buys a better gpu) so im running pentium d 3.4, 700w psu, 2gb dominator, gonna go 4 (board only takes 4 max) cube case and i need a gpu. it fits massive graphics cards in the case, because my dads 8800 gtx was in there for 2 years. what do you recommend me getting that wont get too hot in there? thanks guys.
ste

 

[squarehead94]

my budget is around 100 max for gpu, but if its cheaper it means more money towards ram and stuff so. thanks
also games i play are fifa 12 dirt 3 gta 4 burnout paradise and football manager. thanks
i just need something that doesnt run like lava, something thatll stay cool in a smallish case. thanks

 

[squarehead94]

seeing as though i wont get a reply til later can some answer me this too.
would it be worth going for a cheap amd build? going for an am3+ mobo and getting a phenom 2 x4 or something, i know that i can get the processor and mobo for under 100, whereas the potential upgrade cpu im after (core 2 quad) can cost that alone. what you guys think? thanks,
stephen