Asus 4870 512MB Black Knight vs nVIDIA GTS450?

Hello! I am currently looking to upgrade me GPU, and I work at best buy and get a HUGE discount on Graphics cards, and the GTS450 is the best one we have in store right now and was wandering if it was worth it to buy this? upgrading from a Asus 4870 DK edition.. and also, is the GTS450 better then the ATI5770? And, how much of a performance increase would I see with the GTS450? and i'll be HEAVILY gaming with this card, so should I go with the GTS450, OR THE GTX460?|||Go for GTX 460 1GB version which performs 40-50 % better than GTS 450.|||The 460 is the only one which will show you a performance difference.Your 4870 is faster than the gts 450 and the 5770.There is no need to upgrade anyway.Your current gpu is still great and the radeon 6000 series will soon be released.