MiniSlack
 

I have Slackware 10.1 on a Dell 600m, running very well. I also have it on an old PII 333 desktop. It is slow, as expected. I have heard that MiniSlack runs well on this typer of machine. My questions is, can I achive the same thing by removing some packages and using XFCE, or is the difference more than that? Would I be better off replacing my 10.1 to MiniSlack for this machine?

no, MiniSlack is just slack with pre-tweaking, like Vector is. It is sometimes more convienient to use those distros, but you sacrifice a lot of flexibility. Just make sure you do not use KDE or Gnome and you will be happy. I personally prefer IceWM with a bunch of stand-alone apps for my DE. You can pick another WM or use XFCE if you want.