Things to know, norton and alot of the newer security programs for anti virus and firewalls eat system resources, you need to find software that does the job, but leaves some room for you to work and play. AVG is a very good anti virus, AND IT'S FREE. the best thing is it is light on the resources. Get it HERE
now firewalls are a must have(DONT KID YOURSELF). some that do the job well and save on the resources are SYGATE
and KERIO just click the name to download one. these are both free.
Now spyware, did you get a free screensaver, icons,toolbar or just surfed the net and now your machine crawls? ok, now there are many good spyware removers but i only recommend ADAWARE because some cause a bit of trouble and you need more than a passing knowledge of computers to use them correctly.
there are also programs that manage your ram and resources, like cachman, and .FREERAM XP PRO (works fine on 98 and ME, do not use on XP or 2k as they are not needed). freeram is free and easy to use.....will keep you from rebooting.
ok the rest is common sense, go to your internet options and clean up files and cookies occasionally, do a disk cleanup, and defrag,
REGCLEAN by microsoft is a must have for 9X /ME systems. third party fix-it utilities usually do more harm then good, defrag your system in safe mode if the defrag takes forever or keeps restarting.
If you have XP or 2k and dual boot, there are even ntfs add-ons that make 98 read ntfs partitions, if you cant find one send me a private message here with a email address and what you want like "ntfs file" and i will email you both(they are very small), i have 2, one is freeware, the other is shareware.
USB 2.0 does work with 98 and ME, you just have to find the drivers for your chipset, like VIA,SIS,Intel,ALI,Nvidia,.....
all in all if you can make 98 or ME do almost anything, you can do some pretty cool stuff with NT4 and 95, if you feel like playing with them.

