sounds good...you KEEP the hard drive with you...do NOT send it. the only thing you send is the console...keep your hard drive, power cord, controllers - make sure that any devices you may have connected are removed and also be sure to check and see that no games are left in the console as well. you'll need to contact microsoft and provide mailing information and the serial number of your console. they'll send you a box via ups that has an instruction sheet, packing materials (foam cushion stuff, plastic bag to put it in, mailing label and also a piece of packing tape to put around your box. for good measure i wrote my name and address on a piece of paper and taped it to the console (outside of the plastic bag to put it in) - not necessary, but just peace of mind. and don't worry about your stuff on the hard drive - it's all saved, and if you ever need to re-download anything you don't pay for it because it's already yours (the system remembers you).
be sure to be careful opening your box when it arrives because it needs to be in good shape - it's the one you use when you send it back - you simply stick the new mailing label right over the place where they put the one on to ship it to you. when you go to your local UPS place, it's free to ship it. you can track your order on xbox.com - mine was back to me within something like 8 days (i'm guessing). you will need to be home to sign for it - kind of a pain, but it is exciting when that thing arrives home!!
when it comes back to you there's nothing you have to do...microsoft will have already synced up your hard drive to the new console serial number, so don't do anything except put everything back together.
when i got mine back they also put in a card for one free month to xbox live (gold), so i put the codes in and it extended my current subscription an additional month on top of my current one. so that was nice of them...
i'll post some info. regarding our dynasty over at operationsports - i killed arkansas last night (i'm florida)...i was losing 7-0 then came back to beat them 50-something to 10.
you'll laugh...i'm playing in another dynasty (mac, wac, and c-usa teams) over at operationsports. i'm central florida - played my first game last night against some lower level team - won 98-6. my qb (greco) had 9 td passes. all i did was run late in the game and broke 2 for over 75 yard scoring runs.
i don't know about you, but this is the first time i've ever done online dynasty - it's extremely fun and addictive.
hope you have a good situation with getting your 360 fixed/replaced. btw - they sent me a different one...serial number was dated june of 2008, so i got a different one back. sounds a LOT quieter than my original one.
take care, mike