Hi and welcome to the AT Forums! The more the merrier.
You made the right choice by going with a TBird. Better performance than Intel for half the price. No duh. (No offense to the PIII + PIV folks...my opinion..well fact, actually!

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What do you plan on doing with this proposed system? Email and surfing are a given, that's universal to all systems. Are you a big gamer? Edit lots of digital photos/video? Spreadsheets with 30mb of numbers to crunch?
Others may disagree, but unless you are either running a server or you want to automatically back up your data down to the last bit, you don't need RAID. However, if you buy a RAID board (I did) you gain an extra two channels that can be used for CDRs or other HD's for backup or whatever.
Tell us what you wanna do with your new system and we can hook you up with the info. Assuming you have a monitor, keyboard, mouse, speakers, you can build a nice AMD-based gaming system for under 1K. Lots less if you really shop around.