I have heard that the ATI Radeon can get up2 100 Cmax, nd whilst in games 80 C, which sounds hot. Will 3 fans be enough to keep this cool or would more be needed. and is it really that much hotter than the 8800GTS?

Yea, cards run hot nowadays.
 
Nothing to worry about, nothing will melt or burn.
 
The stock fan on the card will do the job fine, unless the room is very hot as well.
 
If you have good airflow in the case, you'll be fine as well.

80c is fine!
Mine reaches 82~83c all the time!
No worries as Prozac mentioned, all new cards are hot!

but would any extra fans be required if i have 2 x 120mm and 1 80mm fan?

What is your card anyway?

Im going to build a custom PC and i was consedering both cards and was wondering what they where like and how hot they get

Hot indeed.  

I have a 2900xt and it runs at around the 65 degree mark, but when I hammer it BF2 with everything on high it hits 78 degrees, that aint too hot really.

what is so different about graphics cards that they can run so hot?  If a CPU gets that hot, it causes instability.

cpus are 65nm these days, gpus are 85nm these days, the bigger the wiring/transistors the more resistant to heat, quite simple. other things though, when they get too hot they artifact, which is just like instability.

Hoe many fans do u have on your case?

i heard somewhere that overclocked the radeon x850 xt pe could run at 130c, anyone in here done/ heard of anything like that?

No.
 
I seriously doubt that's true.

My 8800 gts 320 runs at 51º C and may go up to 60ªC while gaming