pricewatch.com lists dozens of other site's prices, it can help save some money.
If you're going with Win 7, I would recommend Pro. It offers Windows Virtual PC as a freebie, and gives you a free XP Pro Virtual Machine. It can be handy for legacy apps, or when you need to do testing/etc. Also, Home edition cannot authenticate to a domain, so if you're using this in a work environment, I would highly recommend Pro x64 rather than Home Premium.
The hardware looks pretty nice. I would suggest running your disks in RAID 1. It is faster than a stand alone drive or RAID 5. Plus, it does provide a mirror copy of your data for some level of redundancy. You lose 50% of the total capacity you buy, but it's worth the speed and reliability in the long run. The math of RAID 1 is pretty simple. If you need 2 TB, buy two 2 TB drives.
Just my geeky
