I ended up getting the following from Dell for $649 plus tax (no shipping). 

  * Inspiron 620, Intel Core i5-2310 processor(6MB Cache, 2.90GHz).  Like I said before - a midrange processor.  You can look up computer processor speeds on this site:  www.cpubenchmark.net  I found it very useful when looking at what's out there.  My old processor is about half as fast, and probably comparable to a current low-end CPU.  CPU prices are almost exponential, so I really don't think it's worth it for *poker* to get a high-end processor.  I'm going to get a new machine in 2 years anyway. 

  * 6GB DDR3 SDRAM,1333MHZ.  4 GB is about as low as I would go for poker.  Memory is cheap, so get as much as you want.  But again, when I know I'm getting another machine in 2 years, I generally don't get *that* much more than I need.

  * 1TB Serial ATA 2 Hard Drive 7200RPM.  500 GB is as low as I would go for poker.  I used over 400GB on my last computer (lots of pixels on those horse movies).

  * AMD Radeon HD 6450 1GB DDR3.  Make sure your video card can support at least one 30" monitor (or whatever monitor configuration you are planning to use) - many only support up to 24".

  * Dell 21.5-inch Wide ST2220LB Flat Panel Monitor.  I didn't really need the monitor, but it was only $100 and it was full 1080p, so I just got it.  Who can't use another TV nowadays?  My office looks a bit retarded with 4 large monitors on my desk (30", 24", 24" and 21.5" - two of which can be used as TVs), but it's super-functional.

Dell was having a sale that ended last week, but they have sales pretty regularly.  You can get an extra 2-4% back if you go thru a site like ebates.  Twenty bucks for a few mouseclicks isn't bad, and if you are a shortstacker that's a full day's worth of shoving for you.

The last 5 or 6 desktops I got have been from Dell - you can probably save a few bucks getting some no-name brand, but TBH, computers are so absurdly cheap now that I just can't be bothered to looking around and reading reviews of various brands.  You can also save a few bucks building your own machine, but that's not really something I want to spend time doing.  I'll also be "losing" money on it if you factor in the time I would have to spend on it, so it's really something you should do if you enjoy the process.  All I can say about Dell is they don't suck (which is different from "they are awesome"), and they have decent customer support (except for that one time they routed me to Mumbai for an hour long phone call).

At the end of the day, it only cost me a buy-in and I'm pretty happy with the equipment, so that's all that matters.  Now I can focus on furious mouseclicking.