You can configure it in a cabled-RAID configuration. RAID does not imply Hot-swap.
In order to get the option of hot-swap, you have to select that on the 1st "general" system information page. It'll give you the option between Cable SCSI and Hot-Swap SCSI. Note: There is a difference in price I think of about $100 base and more for the drive. But theoretically you get an included back-plane and hot-swap capabilities (plus I've seen most SCA/80-pin drives going for cheaper than their 68-pin counterparts). I can configure with the free second drive, but I get a price of $1099 before coupon (should be $934.15 after coupon, $834.15 after MIR), so it's about $250 more expensive to go this way.
AFAIK standard P4s cannot run in SMP... thus that's the attraction with the Xeon
Also, for many games it is true that dedicated servers are run in text-mode, but there are a few that I've seen that run their dedicated servers through the game engine, including just a check-box in the host game-setup to run it that way. YMMV, just check the games you want to run to see.