well yes but the problem is finding a wireless card that has windows 98 drivers these days as most have 2000/xp/vista drivers
and if possible you should upgrade to second edition of 98 and get IE 5.5 or 6 as IE 4 and 5.0 can not open web pages anymore without a lot of error messages (windows update told me in windows 2000 that I needed IE6 to use all the update features of windows update)
when 98 came out most of the wireless cards were A or B not G or N
good thing is G and B are compatible (so try to find a used B or older G wireless card that has drivers for 98 like on ebay)
Firefox and Opera can be used instead of Internet Explorer
and you will need java from www.java.com and flash from www.adobe.com for IE or firefox or opera.
and windows NT4 and 2000 will run on that computer too (windows 2000 = NT5, windows XP = NT5.1, vista = NT6, windows 7 beta = NT6.1) just try to get the ram up to 128mb or 256mb as even windows 98 needs more ram to run the newer IExplorer and java/flash and a simple antivirus.
I have a PII 333 with 256mb ram and a 6gb hard drive running xp and a corporate antivirus with a wireless g card that works fine. tho I wish it was a 800~1100 PIII as it can take 3~5 min to get to windows and let me use the wireless from being turned off every night (and it has all the windows updates even service pack 3)