well in your link it shows you have a 8600gts, that would be fine for day to day use, especially since you have a pentium 4. Seeing as you want to use photshop I would think a better cpu would be a better investment, but then again I'm assuming you arent doing porfessional work.
a 8600gts is actually alot better then 7600gt (prob like 4-5 times better) and is an equivalent to a 9500gt if I'm not mistaken. But if you have your mind set on a graphic card upgrade I would go with a...
http://www.newegg.ca/Product/Product.aspx?Item=N82E16814102829&cm_re=4650-_-14-102-829-_-Product