Frency, I thought I had you on my friends list on XBL. Anyways if you already have the 20 gig HD model, then just go and get the Arcade model. It is the latest model. You can tell the newer models because they have the HDMI port on the back of it.
I recently got the RRoD on my premium model I bought last year, I set it back to MS for repairs. Instead of waiting the week it took to have it repaired, I went out and bought the arcade model. It comes with a disk with arcade titles, it comes with a 256 meg memory stick and is the newest version of the Xbox 360. The best part is, it was pretty cheap. I just slapped my old HD on the arcade model and that was that.
When I got my old one back from MS, I put the arcade model away in case I get the RRoD again, I can pull my arcade model back out and ship out my broken one without missing any gaming.
http://www.gamestop.com/Catalog/ProductDetails.aspx?product_id=67291