Here's the scoup:

My box is a 5/6 year old 200mhz MMX computer(i586), with 64MB memory.

It is currently running Slack8.1, with the versions of Gnome and KDE that come with it.

I spent a LOT of time figuring out how to get my USB key to work, how to get ALSA to work with my computer(Had to buy a new soundcard, wouldn't work with my old soundcard, must've been too old that ALSA dropped ISA support), and getting the dependencies to install one of Sun's later Java Runtime Environment SDK, Open Office, and MPlayer(which takes forever to put together....)

Is it worth it for me to upgrade to Slack9.1 when it comes out? Or just upgrade my kernel, or upgrade my GUI's(Gnome & KDE)? If I DO decide to upgrade either my OS or my kernel, will I have to redo all of my steps to get my USB Key to work, getting both of my CD-Rom drives to work, getting permissions all set for my media drives(CD, CDRW, Floppy, & USB key), and will most of my software, like my JRE and OpenOffice still work? Or will I have to reformat basically everything except for my /home partition? Please keep in mind that I can't spend too much time working on getting slack to work better now that school's started....

Id absolutly upgrade.

You'll get a newer compiler/libc, and up to date packages.

I'd hold off upgrading if I were you, since you need it for school. Chances are you will have to spend time working on it to get it set up just the way you want.

If you aren't too broke (right, what student has money?) you might consider installing another hard drive to hold 9.1, then setting up your system to dual boot your old Slackware and the new Slackware. That way you would have the best of both worlds. You could run 8.1 and 9.1 in parallel for a while to make sure 9.1 does everything you need it too. If for some reason 9.1 works for you without too much effort, then you can get rid of your old 8.1 installation and return to a single boot. At the worst case, you'll have some extra hard disk space for that mp3 collection.