Help me make a decision... Please

So, here I am a couple of years after having studiocat build me a quad 6600 rack mount system. It still works just fine. However, I am still running XP 32 bit. I have recently decided to upgrade to win 7 64bit since I just upgraded from Producer 8.5 to X1. As long as I am doing that, I am thinking it is time to upgrade the computer.
I talked to Jim and he gave me a ballpark for upgrading the CPU to a i7 2600, new MB, memory etc..... I intitially was planning to use the i7 970. The thought of 6 cores is just too cool! However, Jim kind of discouraged it saying that the 2600 would be mucho bueno.
At the same time, I'm thinking I want to install a universal audio UAD2 quad card.
 
Interestingly enough, when I research the difference in speed and power of the  q6600 vs the i72600, I find many comments from folks on the web that I won't gain that much.
I do know that my MB (Abit I35 Pro) is limited to 8 mb of ram. I am currently using 4 mb of ddr2 800mhz crucial but upgrading to the 8 mb DDR 2 800 is farily cheap.
 
I am running X1 producer and have a VX700 front end. I use a variety of drum programs and don't use much in the way of keyboards and honestly have zero CPU issues at present running multiple VST plugs (SSL, CW, Voxengo, etc)
 
I guess my decision is if I really need to do the CPU and MB change out.  I know for sure that I want to install the UAD2 Quad and have found a very nice (far below MAP) deal from an authorized dealer. It appears to me that I could simply install Win 7 64, upgrade my memory, install the UAD2 Quad and save the money of the CPU/MB upgrade.
 
Am I going down the wrong path here? Do I just bite the bullet and upgrade all?
 
thanks so much for your comments.

One key question: what do you want to do that would outstrip your current processor?  The 2600 Sandy Bridge would be better than the i7 970 with one key exception: if you are using many heavy duty sample libraries the i7 970 supports up to 24 gigs of ram (as it is tri channel) while the current Sandy Bridge processors only support 16 channels of ram.  Supposedly, tri channel Sandy Bridge chips are due out the last quarter of this year.

Certainly 64 bit has many advantages over 32 bit, especially when it comes to loading sample libraries.  But, for what you are doing or are seeking to do, are you currently running into memory restrictions?  From your post, it sounds like, at least for the present, you are not having problems.

IMO, given the fast pace of change in computer technology, it seems best to upgrade only when one needs to.  Better to hit a bottle neck and then know of a clear need and reason to upgrade, than just to spend money before one really has to, and possibly spend it in ways that subsequently prove to not be of any major benefit.

Thank you...
 
 My current setup has never so much as hiccuped, even running some extensive plugs and drum sample libraries.  I do want to migrate to the Win 7/64 platform from XP  though. This is inexpensive but looks like it will be a pain in the patoot to accomplish.  I do plan on going ahead and buying the UAD2 Quad flexi though.  There current special is pretty cool.

Thanks Jim...