The warranty is over and done
The warranty expires at one point and you are left to fend for yourself in matters of repairs and accessory upgrades. Many gamers have no experience with a screwdriver and would not even know where to start. This means that they have even lesser of a clue where the hard disk or memory chips are. Doing a repair or upgrade that you have no idea about is not very advisable. You may do more damage or wreck the Xbox entirely. The best bet is to take it to the dealer who sold it to you and have the repairs done or give a call to Xbox customer support. This will cost you but it is better than forking out cash for a brand new machine. Authorised dealers will also have genuine accessories which ensures that your Xbox works smoothly or at a higher performance in the event of an upgrade.
Tech support for your Xbox
The Xbox is a trademarked machine unlike your clone desktop or digital camera. This means that the probability of getting knockoff accessories or tech support is very low. Xbox authorised dealers can be found in all major cities. If your Xbox fails, try troubleshooting using the tips in the manual. Sometimes it is just that you have plugged the power cords the wrong way. If the troubleshooting does not amount to anything, you can have a look at your warranty. If the suspected fault is covered, you are a bit safe. You can take the Xbox to the dealer and have it repaired or replaced. Microsoft has terms and conditions that maybe supplemented by the dealer in the warranty agreements.
If your warranty is gone and you have no cash for repairs, you can always ask someone who is good with electronics to have a look. He has to have seen an Xbox before of course. If you have the airtime to make a call to Microsoft, call the tech support and let them guide you through.