Binos,
Sorry about the info overload ....should have looked more closely at your initial post (re novice)
The first part about manually fdisk and format then copying the win98 folder is to avoid the need to have the win98 Cd when you install any new hardware or make a change to network setting or .... or .... (depends on what MS decide at the time

)
The part about changing the drive letter for the CD I would consider V important especially as you mention adding the old hard drive later.
By default MS set the Cd to a drive letter immediately after the last hard drive. that is, if you have one HD (C) the CD becomes D,
If you have 2 HD with 2 partitions on each (C,D,E,F) the CD becomes G.
The problem comes when you install software that needs to acces the CD. If you install when the CD was D and later add a hard drive the CD will be "pushed down" to E or F (depending in the number of partitions). The software then says "can't find xxx" or "insert the xxx cd in D or some such error.
To solve this you need to future proof at the start of an install.
In Control panel the System application has a Device manager tab.
In this tab double click on the entry for your CD in the CDROM tree.
In the settings tab you can then change the drive letter in the Reserved drive letters section. (make them both the same).
you will need to reboot after to effect the changes.
Sorry about the lenth of the post but I thought I had better spell it out
MAx