Exactly what I was going to suggest. For the price of a hard drive there is no point in burning your bridges.Word of warning, though, don't install your old drive as the slave until AFTER you've installed Windows, or problems can occur.
I reformat drives for Win95 (this applies to new drives, too) by using a specially prepared floppy:
Format a floppy with system files included. Add the files FDISK.EXE, FORMAT.COM, HIMEM.SYS, MSCDEX.EXE, and a driver file for your CDRom drive - usually available from the manufacturer's bulletin board.
In case of difficulty, email me via the 'clicky' and I'll send you a 'universal' driver which usually works.
You then need to make a config.sys file:
device=himem.sys device=(driver name).sys /d:MSCD0000
and an autoexec.bat file:
mscdex.exe /d:MSCD0000
These must be on the floppy to allow the CDRom to be accessed, and himem.sys is necessary because Win95 setup needs to run scandisk, which won't work without himem installed.
For Win98, you really need the floppy which is normally shipped with the Win98 CDRom. There are files on it required by Win98 setup, but you may well be able to download it from the Microshaft (oops! SOFT!) website.
At worst, I could email the vital files to you. If you've got a genuine copy of the CDRom, you are entitled to the files.