Hmm. I'd tend to agree with Beorn here that it could be the RAM fried a little. I'd need a bit more data to work with before confirming that, though, since usually bad RAM brings with it BSODs.
If you can remember the rough time and date of the power outage, could you look in the Windows Event Viewer and post details of events logged around that time, as well as after the computer was booted up again? (Event viewer is located in the Control Panel under Administrative Tools)
Another good diagnostic method is actually Dwarf Fortress. I tend to use it for stress testing things at work, and it works remarkably well for that purpose. Generate a few worlds with it, one after the other (Standard size, I should add) and let us know if it crashes the computer.
As for the sound issues, try reinstalling your sound drivers first, see if that does the trick. If it doesn't, let us know.
A couple of other questions, too, before I forget.
* What version of Windows are you using? I'm guessing XP, but is it Home or Pro?
* Desktop or Laptop machine?
* What are its specs?
* Self-built or branded?
* Pepsi or Coke?
I think you may be able to recover the machine without buying new hardware, or reinstalling windows or any of that. If you know how to, you could run CHKDSK/p from the Windows recovery console. If you don't know how, and the tests I outlined above bring no further facts to light, I'll explain in a later post.
Best case scenario is that your PC just lost a little data in the power outage. Worst case is that you have to buy some new RAM. And punch your brother. Lucky for you, if your machine uses DDR or DDR2 RAM (the DIMMs with only one notch), it's fairly cheap right now. If you're unlucky and your machine uses non-DDR SDRAM (the DIMMs with two notches), that can be fairly expensive to replace.
Apologies for wall of text. I just like to at least try to be helpful.