I got a vga plugged into my 19" crt monitor and there is a big difference from running it on a standard tv, much sharper gfx i was impressed with the difference.
When you boot up and go into 360 dashboard you are given different resolutions, ones i remember 1024x768 and 1280x1024 i imagine these the most used. Then you can select widescreen or normal option, now the only real thing is on a normal crt when you put it on normal you get borders top and bottom(unless u got a widescreen one) as you would expect.
Then if you put it on widescreen it fills the screen but makes everything look squashed, now personaly it doesn't bother me having a border as there is a big difference in graphical quality over a standard tv, the details you miss out on are there to be seen.
I can see one problem you may have is finding a vga cable they in short supply atm.