I don't mean to insult anyone that has posted previously,
but I have always had incredibly good luck with the genius bar at my store.
they always make sure they take care of any machine that is put into their hands, and they are extremely quick ( they strive for a 2day turnaround time maximum. )
if you come in there guns blazing, no one winds up happy. trust me.
but if you come in with a cool and collected attitude they're ( speaking from my experience here YMMV ) very easy to talk to and work with and get the problem solved.
1- i brought in my refurb G5 to them because my processors and power supply were faulty, they had it back to me in less than 2 days and i've never had to take it back since.
2 - i brought them my powerbook g4 to replace the screen due to banding, they replaced the screen for me and had it back the SAME DAY. and again, i've not had to bring it back since.
3- they do stock mac pros in the back, 2.66 standard spec, and some 3.0s with 2GB of ram ( in comparison to the standard config )
don't be afraid to go to the genius bar, just dont act like a jerk to them and they will be more than willing to help you out.
theres my 2.5¢ for ya