As far as a light WM, get Fluxbox. It's blackbox, but nicer looking.
As far as getting it better looking, if you have the HD space, you might think about installing the dropline gnome distribution, from www.dropline.net
. It has a tweaked XFree package that gives you really nice font rendering, on any window manager you do end up using. It also comes with some other nice packages, like a version of Xine with all of the supporting packages to play encrypted DVDs out of the box. I personally love Gnome. It just helps to have a good bit of memory to use it, which is about 10 cents a meg for DDR right now in my area. Gnome has a very clean look. If you want to see some screenshots of Gnome in action, just check out art.gnome.org to see them. I installed KDE as well, because sometimes I like to use it, and I have a lot of HD space. Gnome is definitely my everyday use desktop environment, though.
Fluxbox is available on the Slackware FTP site, as well as all of the mirrors, as a Slackware tgz package. It's under Slack 9 in the extras directory. I assume you've used the Slackware package system, but if you haven't, just ckeck out the man page for pkgtool. You can also run any of the initial setup scripts from there, as well as check out exactly what files a Slackware package installs. There are also some command line package utilities. I'm sure there's info elsewhere on the forum.
Fluxbox is pretty easy to configure, too. The look and feel can pretty well be tweaked from within Fluxbox, and there's a .fluxbox directory under your home dir where all of the config files reside, including the one for the fluxbox menu. Blackbox is also available on the FTP site, but Fluxbox is really the same thing, but slightly easier to use, and a little better looking.
I hope this helps you out. Welcome to the wonderful world of Slackware. I don't think you'll be at all disappointed with it. Nobody ever is, as long as they're not scared. And, there's nothing to be afraid of with a pipe-smoking penguin.
I would also advise, if you do like Slackware, help our friends and buy a copy from the Slackware store. The CDs also include all of the extra packages from the FTP site, the kernel source, zipslack, the bootdisks, and the live cd -- ideal for converting people to Slackware!