I have a very crappy power supply and am worried about having power issues if i put my new hard drive in as a second hard drive. I recently put in a new graphics card that is a power hog compared to my old one (128 mb 9800 pro compared to a geforce 4 mx 420). My computer is really starting to get sluggish (havent reformatted in 2 years). So, instead of putting my second hard drive in and backing up data and reformatting, I was wondering if this was possible: could I just replace my old hard drive (120 gb) with my new hard drive (200 gb), boot from the windows xp cd, partition it and install windows xp? If I wanted to go back to my other windows for some reason, could i switch out the hard drives again and boot from that windows?

Thanks

yha, u should be able to boot from that old hardrive, if u havent formated the old one.

if ur power supply is so crapy why dont u just buy a new one.

What wattage is your power unit? It won't be the reason for the slowdowns. A genral buildup of rubbish on your Windows drive will be doing that

correct, a lack of power will lead to hardware sometimes not working.
For example when I first installed a DVD writer one of my harddrives would no longer work, but only AFTER I'd used the DVD drive.
After rebooting the drive would work again.
When I disconnected the DVD drive the harddisk worked flawlessly.
That's a clear sign of lack of power, a general slowness of the system is not.

I know the power supply isn't causing the slow down. Its definately the hard drive, since it hasn't been formatted in 2 years and is full of junk. The reason I was talking about the power supply is because I'm afraid if I put my second hard drive in to back stuff up before formatting, that it will cause problems because I doubt I have enough to power from a 250W power supply to run 2 hard drives, a cd burner and a dvd burner, and my 9800 pro.

Anyway, I think i've just decided to buy a new case (w/power supply), motherboard, processor, and ram, and build a new computer out of that, and out of my old stuff (and put my fresh 200gb hard drive in there). This will only cost me 400 dollars or so, and the reason I'm doing this is because I wanted to upgrade my RAM but discovered I can only use RDRAM, which would cost me 200 dollars for 2x256 sticks, when i could spend less than half that for twice the RAM if I upgraded to a mobo/processor that used DDR.

Okay, and sorry I neglected to answer your original question.

You can install a new replacement drive, partition it and install Windows XP from the XP CD. You can also swap your original drive back in later and it'd work, as long as you don't change much hardware.

You can't use your original drive in a newly assembled PC, because Windows won't boot in the new machine - but you can add the original drive as a slave drive in the new PC and copy your data across.