you should have the original disks that came with each component, no? the drivers should be on those.
you can get all the drivers you need for free on the web. please post the make and model of each component, including the monitor, video card, sound card, printer, motherboard (or PC system if you don't know specifics), etc.
a lot of companies have dropped support for windows 98 now, tho, so you may have a hard time finding stuff if you don't have the original disks.
as far as upgrading to 98 SE, 98 is very picky when it comes to upgrades. if you have a 98 SE disk, you can boot from it and then install it into your existing windows directory, c:\windows. It should handle upgrading everything.
A word of advice: If your computer is anything faster than 800Mhz with around 256MB of RAM, upgrade to Windows XP. It's worth it. All of the drivers will be included for your PC and things will work A LOT better. Seriously. All of your games will work, and if you can't get something to work, it should work using the free DOSbox software.
If your computer is slower than those mentioned specs, please go to Walmart or wherever and drop $400 for a new PC. You'll thank yourself later.