Asking for help reviving an older machine?

[VistaHome32]

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OK, it has been a while since I started this Vista PC (since it having troubles), but am now seeing if I can ask some experts here for a little help? This machine/OS has been giving me sone screwy problems (sys restore not working, win update was giving quite a few problems, even some of the tools were acting like portions of the programs were corrupted). I tried sfc but it found nothing. I finally found a system disk (DVD) with all the versions of Vista Ultimate, and am wondering if I can use it to FIX the files so they actually work again (yes, even though sfc didn't find anything to fix, I am thinking the OS is corrupted somewhere).

I have a few games and programs that I cannot find the disks to (a couple were downloads paid for and maybe stored on the multutude of HDD's scattered around), the hiccups affect the games and programs. I am not sure it is a hardware problem (a few mini-strokes makes this effort harder). I know I can easily wipe the system BUT this was an update to Ultimate from Home, and I have no idea where the new key is (and if it will still be able to validate by phone from Microsoft). Also, the games and programs issue...

So, IS there a way to reinstall/repair without losing everything AND without having to a long convoluted step by step procedure (those mini-strokes sure limit my thinking processes).

Thanks if possible, but if too complicated I just might as well give up completely(?)...

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