I just got my 360 back from M$ yesterday after sending her in because of the RRoD. I am glad I sent it in when I did and not wait it out (I was doing the towel trick to keep it running). The whole process took about 20 days (from initial service report). The console I sent in was manufactured in Dec. 2005 and the one I got back yesterday is manufactured in Feb. 2008. The bad boy runs a lot cooler and way more quite.
GTAIV was one of my main reasons for sending it in when I did and making sure I got it back on time.
Best of luck to everyone owning an older model 360, the failure rate on launch systems is through the roof! I'm surprised mine lasted as long as it did. May you all take care of your systems, at least until you've had your fill of GTAfizore.