I bought the ZT system from costco online. At the time they had a model with XP Pro, with the AMD 64 chip which can run 32 or 64. I am set up with the 32 bit XP Pro, and it works beautifully. 500 G hard drive and 500 external seagate free agent HD for backup. Mine was only about $800 which included a 22" LCD monitor, and the Costco Concierge service is pretty darn good for helping to set up any electronic items that you buy from Costco. In addition you get what I belive is double the mfgrs warranty from costco at no extra charge.

All in all not a bad deal. If you need 64 for other reasons, then I guess its a moot point.