My old computer wouldn't turn on , and everytime I turned it on the whole graphics card fan would go really loud(louder than when playing games) and then the monitor wouldn't load at all. I took it to a local comp store and they couldn't get it to turn on either. Is my hard drive still reuseable for a new pc? Also, will I have to buy another OS disc if i reuse my old hard drive since the OS is already on there? I am willing to buy a new one but this option would save me well over $150.
Thank you for your time
You can reuse the drive, and possibly the OS as well. Assuming the drive is good, simply plug it into the new system. If you want to save your data, boot from your OS disk, select install, and tell it to install on your drive. It should find the old windows build, and allow you to install over it, saving your data files. If you don't care, format the disk and perform a fresh install. If you don't have a windows disk but a resore disk, your OS is tied to the motherboard, and can't be used.
Hard Drive: There's no indication that there's anything wrong with your hard drive. If you are building an entirely new computer AND if your hard drive isn't new (say 250GB or less) then consider buying a new one such as a WD 1TB Black as your main drive and use the older one for backup. If you go this route, I'd put two partitions on the new drive and do a FULL format of your old drive (FULL builds a bad sector table to isolate any problem read/write areas). You can also do a full diagnostics using your hard drive companies appropriate disc(s).
Windows: Usually, what you have is an "OEM" copy of Windows as opposed to a "FULL" version. They are identical in software but OEM copies cannot be transferred. They are essentially tied to the motherboard. I've heard of cases where people got a motherboard that was ALMOST identical (same main chipsets) and were able to REACTIVATE with Microsoft.
CLONING: If you can an almost identical motherboard like I said with the same main chipset you can try cloning. If the main chipset isn't the same you may have too many errors. Also, if you can't get the same motherboard AND have an OEM copy of Windows it's pointless as you'll need a new version of Windows anyway.
If you end up having to buy a new Operating System, I highly recommend getting the FREE version of Windows 7 RC 64bit. It's good until end March 2010 I believe. You will want to look around for an OEM copy once released which will hopefully be no more than $120 USD (Windows 7 Premium 64bit).
Your computer store doesn't sound like they did a very good job. Did you pay them without at least a diagnosis of the problem? Did they swap out the video card or PSU?
It's likely only one part that is the problem. If it's the motherboard you can try an IDENTICAL replacement (to keep your OS), a replacement without the same chipset but that DOES enable you to keep your CPU and RAM, or else get a newer one and rebuild most of your system.
Troubleshooting Part 2:
Graphics card: try to borrow a card or put yours into another system
PSU: hard to do anything without a spare PSU. It's probably not the problem but if you can borrow one that's great. If not, consider buying a good one such as a PC Power and Cooling or Corsair that's 650W or so that you WOULD put into a new system if you fail to resolve the problem. At least you wouldn't waste any money by purchasing a part just to troubleshoot and not use if it's not the problem.
Without knowing more it sounds like your graphics card or motherboard. Definitely try to test that graphics card. Any half decent computer store should do that as standard practice.
First, take the computer to another shop. The one you are taking it to is going to screw you big time. Unless there is more going on than what you have posted here, get your PC out of that shop.
Sounds like all you need is a new graphic card, even if you are running onboard video, you should be able to put an inexpensive graphic card in the machine.
If you have simply decided it is time for a new computer, yes you can carry the old hard drive over. But whether or not you can reuse your copy of Windows is another problem. If is was an OEM version of Windows in a prebuilt computer, no you cannot reuse it. If you have a retail version of Windows that YOU bought, then yes you can reuse it. Either way, you will have to reinstall Windows on the new PC, you cannot simply transfer the installation and expect it to work.