Best Video Card for Me?

Hello. Recently I have been looking to buy a new video card. Except, I don't know what is the best at the moment. I'm looking to spend about $300 AUS (which is about $210 American, according to a converter) on it.

My Specs are: Intel Core 2 Duo E4600 - 2.4GHz (quite old)
2 gb ram
SLi and XF Ready Mobo.
currently ATI 3850 GPU.

My monitor only supports up to 1280 x 1024 resolution, so i want the best card to help achieve this and high settings in most newish games.

all help is appreciated.

Thank-you.

+1 for the 4850 and if you have some money left, get some more RAM...
But for that resolution, even the 4830 is suffice...

to jennyh. Thanks for the reply. I do want to upgrade my cpu, but lacking in the money, so can only do small things at a time.

to gkay09. I was thinking of getting some more ram anyways. get another 2 gig or so. but thanks.

to morfinel. its Pci-e 1.00.

thanks for all the replies.

will the 4850 allow for me to run gta 4 at a decent graphics level? i can run it on low atm with my current card, but i want it to be better.

Also, when you say the 4850, the 512mb or 1gb memory?

thanks.

btw. if this helps at all, i run xp (SP3) and got a 430 (or 420?) PSU. - forgot to add that in my specs.

I know that GTA 4 is a high demand game, and that the quad cores do very well with handling it. I am not expecting the highest settings from my comp. just a little bit extra, so that i can run it on decent settings, medium - high.

as mentioned above, I will look into upgrading the rest, just not at the moment. why would i need to upgrade my mobo?

i got a thermaltake 430w psu that came with my case.