"Factory Restore" or Not?

Win ME: I've installed & run all the programs recommended by your superb site.
My systems come up clean, but everything has slowed down in the intervening 7 yrs. I'm at the end of my rope. If I wipe out the hard drive & reinstall, will I be able to download all the patches for this OS from MS again? Or is there a way to save all of them for quick reinstall? Any suggestions to improve this system's
efficiency (presently about 65%) would be greatly appreciated! I don't ask much of this thing except an internet connection for research, email, etc. I'll even pay for some help over the phone if reasonably priced, but I can't be on both simultaneously.
Thanx