Help Need a new Graphics Card "i think"

[davejessop]

Hey I have a hp m7757c media center pc which currently has a Nvidia 7500le graphics card...well now my problem...at first after about 20 minutes my screen would just go blank so i switched out monitors still have the same problem so the only thing i can think of would be the memory card i thought i would just buy a new one but my psu is only 300 watts w/ 12v~~19A rating so with out replacing it i can't find one so?
Does this seem like the problem?

Any ideas on a new card?
Thanks for all your help in advance....

 

[saint19]

First verifies if is the GPU or the RAM...and the options could be a ATI 4650, or a 8800GTX...those are good cards.