Whether it be an old system or a kick ass system *like my gaming system* when it comes to games win98 is way ahead with flying colors win98 put your hardware + its abilities at your finger tips. u wont mistakingly hit winkey and lose ur sound in win98. no other os gets the same results out of my sblive 5.1 platinum like 98.
At any given specs try 98 + any other os with the same game and 98 will run circles around them.
only problem with 98 is accessing large drives (where u'r games r usually stored)this given the limitations of fat32. plus the overhead of accessing/addressing large partitions/disks is usually another factor.

BTW @Devilism dont create a separate partition for your swap file unless its on a disk thats isnt being accessed otherwise whilst ur playing ur game or doing your other stuffs. this will increase the # of read/write commands ur hdd as to execute(slowing the whole process).