I hope I'm not stating the obvious...the difference between widescreen and regular is the aspect ratio (16:9 vs. 4:3). You could do some math to see how that translates into screen real estate when compared to your current monitor. Widescreens are wider and shorter than 'regular' screens. I have a 22" widescreen, and can see columns A-Z in excel. I love that! I have another monitor (17") that I hope to one day put into dual screen; right now it's hooked up to the xp machine, which holds the certificate for signing code.

I dont dislike Vista, but I'm not wowed either. I can do everything I did before, and all of my older programs run (dreamweaver and fireworks mx are biggies for me). I'm running 4gb of ram, and about 3.5 are recognized. 64 bit versions of vista/XP recognize more ram, but comes at a potential cost of compatibility.

XPS is Dell's gaming line, right? if gaming is not an issue, why not go for something else that XP ships on? Every system I've seen with vista that has a dedicated video card and 2gb of ram does pretty well (although XP would do better, performance-wise). More ram is always better, and pretty cheap these days.

I build my computers as a hobby these days more than anything else. It's not really any cheaper, although some would argue the quality of the parts is better. I dont know enough about dell, hp, etc. to comment on their quality, but that's what i've read!

regarding your video card question, get the best you can afford - but top of the line is not needed. Newegg reviews were quite helpful when I was deciding. I think nvidia has a leg up at the moment. I think you should get one that can run dx 10, if I recall my research.

good luck!