The "virtual memory" that Aida refers to is actually TOTAL memory (physical RAM + virtual memory). Thus: 1792 MB swap file + 255 MB Ram = 2047 MB.
Onca all your physical RAM is in use, Windows then begins to utilize the swap file. In this case, all your RAM is in use, plus another 190MB in your swap file.
The swap file is larger than the physicaal RAM for a very simple reason; it gives Windows much more space in which to load programs and data. Take a hypothetical case... Windows 95 running on only 8 MB of RAM (this was actually the case when I got my first Win 95 system). With only 8 MB RAM, Windows can barely load...without virtual memory, you would be able to run NO programs (in my case it was so extreme that merely moving the mouse would cause the hard drive light to come on!) By using the swap file, Windows is able to load and run programs that simply won't fit into your physical RAM. On the machine I'm using as an illustration, I actually did a lot of graphics work (a very RAM-intensive operation)...it was slow, but it got the job done (needless to say, I added more RAM as soon as possible).