As far as migration do you mean you want to dual boot or migrate completely to linux?
The process would be quite different depending on that, be a bit more specific about exactly what you want to do and I'll check back.
I would say that you might want to think about at least getting a newer version of redhat though, 8 is no longer supported, don't think 9 is anymore either...if you wanna go w/ redhat maybe RHAS3.
And redhat is still an excellent choice for servers...not to say that slackware isn't. Mandrake is great too.