Regarding using SP2 and the firewall... the firewall becomes very usefull for those of us that travel and leave the safe confines of our homelan security zone.
I have never used road runner so I don't know what they are using for their internal ip addressing scheme. Could be picking up the address form a rogue DHCP server. Regardless, it looks pretty hosed.
I have the http://www.lacie.com/products/product.htm?pid=10461 I use it as a backup target. It's bigger and heavier than the typical external Maxtor drive so it's not something you are going to drag around in your backpack very often.
You can build an external array that does the same thing as the Buffalo Tech product. However, they have a really nice case and Buffalo builds great products. I'd like to get my hands on the 1.6ter unit.