possible overheating of card?

every time im playing medal of honor online my fan keeps going mad every 5 minutes. it never used to but now i cant get a good game in cos its so bloody loud and distracting. does anyone know why? i dont know what fan it is as its the one that came with it in the shop.

p4 3.2ghz
1024mb ddrram
geforceFX 5500
250 gb hd
xp sp2
 
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