So how will the performance be?

I know that at this stage this cannot be accurately ascertained. I mean they are still working on the engine. But based on statements (not set in stone) in an in depth interview that the Sandybridge architecture would be a ballpark estimate.

I ask this because I'm going to try to raise money to build a desktop and with the current prices and stock of certain parts I might want to grab the proper case and mobo soon. This would of course determine what kind of graphics card, hardrive and CPU I would be using. Getting an estimate would also give me a proper benchmark rating to look for.

This three year old laptop served me well for SMNC but I'm certain is at its end.

Look into Tom's Hardware system builder marathon articles.

Wait as long as you can, then buy the fastest system you can. For a host, bias you purchases toward CPU/RAM, for a client bias towards GPU/CPU. Anything more detailed that that you're gonna have to wait a hell of a lot longer.