I know the meaning of upgrade. I have done it before.
The problem is that if you upgrade, leftover ununsed Registry
entries (except for WINDOWS' registry entries) for unworking
programs remains, and uninstallers specifically programmed for
Win98 will not work in Windows 2000 because Win2000 uses the newer
WinNT Windows Kernel and API system. (Same as now, when Vista
arrives, probably the programs I made will not work there)
In this case you have to
* Manually remove program files from your C:\Program Files, but
Registry entries remain and clutter up (registry hives are huge,
takes up a lot of space and fragments easily, bringing performance
down)
* Use a program cleaner like Norton CleanSweep, which can remove
DLLs, Registry entries easily;
* Do a clean install to clear all useless not-working program
files.
You can backup Firefox passwords, bookmarks. You can backup MSN
MESSENGER contacts. You can backup your Windows Media Player
playlist.
Lesser files in your system represents better performace. Since
your Win2000 CD is a FULL VERSION, it is best you clean
install.
Feel free to ask more.