paging file is like ram on your hard drive. u add your RAM size(eg. 256mb) and your paging file size(eg. 512mb) to find the amount of memory available to your computer. your computer will use your RAM and paging file for your applications, games. of course u know that RAM is much, much faster than a hard drive. so the more RAM, the less need for the slow paging file on the hard drive. most people are saying 1gb of ram is enough, this amount will give best game performance. don't turn off your paging file unless u have a crazy amount of ram. your system won't go faster, by turning it off with little ram, u will get memory errors...
i was just suggesting for the boys with 1gb of ram into gaming only, to try turning off the paging file to see if 1gb is adequate amount. if it is, we shouldn't memory errors. if we get these errors, then we could possibably benefit from even more ram..
Pentium 4 3.0Ghz, 1Gb pc3200
BFG 6800gt, samsung 19\"
Audigy 2 ZS, TruePower 550 watt
3Dmark05 - 4750, Aquamark3 - 59 200