Are console VGA adapters worth it?

I'm playing all my consoles (PS2, Xbox, Dreamcast) through an old TV in my room that only has RF input, so the quality is obviously not the best.

I have a 17" LCD monitor on my PC and am wondering if I got a multi-console VGA adapter that I could use to connect my consoles to it, if the quality would better.

My Dreamcast is Japanese and the TV is PAL only, so all games come out in black and white, so I obivously haven't spent a lot of time with it and it's a hassle moving to another room in my house with newer TVs. I'm going to get a colour modchip for the DC for about $20, but if VGA Adapters are cheaper than that and I can run all my consoles through an LCD monitor in better quality than on a RF only TV, then I'll probably go for that.

What's the better choice?