It is a swap file, I guess you have 256 MB of RAM in your system. Windows still pages files between memory and the hard drive in order to function, so you should not delete it (you may not be able to and if you do it will only reappear). You can decrease the size of it by decreasing the size of you vitual memory: but you may get a drop in performance. Besides, 250 MB is nothing in todays world of 120 GB HDDs. Incidentally, on Windows NT/2000/XP systems the file is called pagefile.sys