I think the A1 is the retail version and the TR is an OEM. They are the same board though. Things that would differ might be the contents of the package and the warranty.
Thanks for all the advice so far. I think I am going to use Windows 7 as my main OS so I'm probably going to go with the G.Skill RAD mentioned in his post. Now I just have to decide on which motherboard and what HSF to go with.
1) What will you be doing with this PC? Gaming? Photoshop? Web browsing? etc
*** Work, Gaming, some light photoshop/c4d/vegas and general computing
2) What's your budget? Are tax and shipping included?
*** $1,000 to 1,200 before Tax\Shipping
3) Where do you live?
*** NewJersey
4) If...