In this case, IMO, you’re mistaken. The OP’s PC is more than capable of running XP.
Hey, I have an Athlon XP 1800+ with 128 Mb of RAM running Win XP and my Mozilla takes almost ten seconds to load initially. I think it’s just some problem with Mozilla, and it’s this close to making me go back to IE.
You folks having problems with Mozilla taking a long time to load; have you tried turning on “Quick Launch”?
So here’s the update: I went ahead and held off on buying Windows XP (thanks for the encouragement to wait). I mean I’m sure my computer could handle it, but if it’s not going to make a difference speed-wise then I think I’m probably better off without it. I did, however, download Firefox and you guys are right, the thing is pretty fast. So now I’ll just do some more research about how to get the most out of my RAM and I should be all set. 
If you’ve got enough RAM to spare, I second Revtim’s suggestion for using quicklaunch. It makes a huge difference in load time when you initially start mozilla (it’ll load almost as fast as Firefox). I don’t use the option on my home PC though, because if I’m not web browsing I generally need the extra RAM for whatever else I’m doing.
Haven’t tried Firefox in a couple of months, might have to give it a spin again.
I have to use IE at work, and it drives me crazy. Tabbed browsing is wonderful.
DooWahDiddy, if you’re going to do a complete reinstall, spend a couple of evenings going through and making backup copies (to CD or another harddrive) of EVERYTHING, and I do mean everything that you can’t just reinstall. Documents you’ve created, MP3s, saved movie clips, save files for any games you play regularly, IE bookmarks, saved email, and whatever else you think you might concieveably want to keep around. (If in doubt, keep a copy. CD-Rs are cheap).
If you have a fast internet connection, go to microsoft’s website and download the most up-to-date service packs/security patches that you can. Burn these files to CD as well.
Then do a complete reformat of the hard drive and reinstall '98.
BEFORE you connect to the internet, install all the updates you downloaded from Microsoft. This’ll help you from getting 0wnD by any script kiddies that could easily attack a freshly installed OS.
Then reinstall all your applications (including Mozilla/Firefox), restore your files from the backup CDs, and you should be set.
Why would be the purpose of that? 
There is no need to reformat when reinstalling Windows 98. Here’s an easier way:
Copy the whole CD to a subdirectory on the HDD (e.g. c:\install).
Create a boot floppy and boot from it.
Rename c:\windows\win.ini, c:\windows\win.com, and c:\windows. Also rename the c:\Program Files\ directory. This will prevent the Windows installer from seeing your old copy.
Install Windows from the HDD.
Now, if everything goes wrong, you can just boot off your floppy and unrename everything and you’ll be back where you started.