Microsoft recently extended the warranty on 360's - as long as its related to any red ring of death shenanigans.
Fortunately (and believe me, this will probably be the only time i'll say "fortunately" to this) it sounds like your problems are the early symptoms of what becomes RRoD. I should know, it sounds like the symptoms I went through that resulted in me having to get it sent off for repairs.
The best thing you can do is ring up Xbox Support. You'll probably need the serial number off the back of your 360. If they determine it to be red ring related (which they should by the sounds of things), they'll give you a number. If you bought it in a shop and still hold the reciept, box the 360 up, take it back to the shop, explain the situation and give them the return number you got from Xbox Support. They should give you a replacement there and then. Depends on the shop really. Also, remember to take off the hard drive before you take it back. You wouldnt want to lose all your saves now, would you?
If you bought it over the Internet, or they refuse to take it back, you'll have to send it back to Microsoft. Fortunately, they will pay for UPS delivery and have someone come and pick it up. Again, all you have to do is box it up (sans hard drive, obviously) and apply the appropriate labels. Alas, the turnaround time on this is "up to 25 working days" - 5 weeks basically. And, based on personal experience, it took me 5 weeks to get it back.
I think that about covers everything. If there's anything else I can dispense my sagely advice upon for you, please feel free to reply to this.
