hello everyone

recently,,, on one of my friends PC ,, which was copying somewhat slow,, (his is 64 MB RAM ,PIII system,, running win 98),, i did a small tweak in system.ini,, and then i went ,, after some time my friend came back saying tht his root drive (i.e. C drive) was showing win386.swp file of approx 126 MB and previously,, i mean before i edited system.ini ,, it wasn't there,,,, i told him tht swap file r always there in windows sys(atleast in win 98 it is there,, i couldnt locate win386.swp on my system running winXP pro) ,, and it's size depends on many factors and i also told him tht y windows create swap files,,, though i'm still at sea as to y my box didn't show any swap files,,,anyways ,, back to the problem,,, now that file is not deleting and when i try to shift-del it, it simply said tht the access to this file is denied giving some type of error in number and tht make sure tht the disk is not full or write protected,,,,
now i want to delete it or for tht matter,, i wanna know how can i delete it,, even though it is not advisable to delete it...,
..secondly what is the exact basics behind these swap files created by windows....
any help is highly welcomed

thanx in advance