Looking for suggestion on upgrade for graphics card

I currently have an ATI Radeon x1600 pro 512 mb ddr2 card.
I am looking to upgrade for something that is dx10 compatible and I am looking at the GEforce 8600GTS OC with 256mb gddr3 card.

In comparison of the two on memory size (512mb ddr2 to 256mb gddr3) am I losing out performance wise? From what I understand the gddr3 is better, however, between 512mb and 256mb am I losing out on any performance between the two?
Should I save/wait for a 512mb gddr3 card?
Should I just keep my 512mb ddr2 card and just upgrade my 2gig(1gig stick and two 512 sticks) of system memory for 3 gigs (three 1 gig sticks)?

I have not had any major issue between ATI or Nvidia cards and I do not have a preference of one over the other.

Just looking at recommendations and suggestions.

you'll have a huge performance boost when using the 8600GTS

http://www23.tomshardware.com/graphi...54 &chart=316

Waiting for the 512 over the 256 for me would come down to price, if it won't be much more expensive and you can wait then grab the Geforce 8600GTS OC with the 512mb of ram when it is released. The 8600s are already quite cheap compared to their higher end counterparts.

And if this is any indication...
Newegg.com Biostar GeForce 8600 GTS w/512mb of GDDR3 for $215
I'm sure the OC versions of the card won't cost much more than this.

What it really comes down I would say is if you are running XP or Vista. If you are running Vista, go with the RAM upgrade for now. Videocards will only get cheaper by years end. If you are running XP and you need better graphics performance get yourself a card.