There are lots of ways to hook it up, but they vary greatly in quality and price:
1) You can buy a standalone component video ----> VGA adapter. These are the priciest solutions, but will allow for any HDTV signals to be displayed on your monitor. Viewsonic sells the N6 for $330 to $400 and essentially becomes a video receiver for your HTPC. There are also various VGA boxes (~$200) that do the same thing with less options, just straight component video to vga. The benefits of this option are that the resolution will be much higher b/c your monitor will display the HDTV quality 480p signals from your XBox. This option would also require you to purchase the XBox HDTV AV pack b/c of the XBox's propriety system interface.
2) VGA adapter specific to the XBox. This option is considerably cheaper than the above option, and serves as a simple break out box like the Advanced and HDTV AV packs that M$ sells. There are a few of them out, but basically they plug into your XBox, you plug a monitor to its VGA out, plug in your sound type (Toslink or composite RCA) and you are good to go. This option is only really suited for people that have a KVI switch or a monitor with dual inputs (ie DVI and VGA, or dual-VGA). My 1900 FP supports dual-input with a switch on the bezel. These go for ~$70-$90 shipped. Again, these boxes will give you the benefit of HDTV 480p on your monitor.
3) There are also adapters that claim they are VGA adapters, but they are only really "line-doublers". What this means is they just take the NTSC (non-HDTV) signal from the XBox and de-interlace the signal. They are cheaper @ ~$50, but still leave much to be desired and the same effect can be done with some tweaking on your PC through video overlay.
4) The last option is as Kk4JC said, running it through a video in on your VIVO card or through your TV tuner card. If you go this route, S-video is the only way to go as composite video looks absolutely terrible and isn't worth the bother. TV Tuners use video overlay, and with the help of programs like DScaler, you can essentially use your CPU to do what the Redant line-doubler does. I'm not sure if VIVO cards use video overlay or use hardware decoders for NTSC to VGA, so YMMV on that.
5) I haven't researched this last option, but I think it would probably work. If you found an HDTV tuner card that allows for component video inputs, you could also get 480p from your XBox. These are also pricey though, and since I have no other HDTV source, not a necessity for me. Around $200 IIRC.
Here's how I currently have my XBox set-up:
XBox advanced AV pack with S-video going to Asus TV 880 tuner card's breakout video-in box. Optical toslink from AV pack goes straight to my Sony STR-DE545 DTS receiver. To switch between XBox and PC, I simply switch the receiver to TV/SAT for 5.1 DTS sound and in PowerVCR II I switch video input from TV Tuner to S-Video from the pulldown menu. The quality of the image is still very good considering so much has been interpolating in scaling the image to 1280x1024 (my LCD native resolution). Also b/c I have the new CX880 encoder/decoder chip on my tuner card there is no Dscaler support yet (in progress). Some games look better than others, as I'm sure it has to do with the game's resolution. If I had to make a choice from the options above, I'd go with #2, but I'm gonna wait a bit as my IQ is good now, and I'm not sure how much better 480p would be (I'm sure it will be improved, but for the price I dunno). Also, the use of video overlay is nice b/c you can window your XBox (while waiting for Live! games to launch etc.) and use your PC normally to do whatever you like in the background. Only thing I wouldn't do in the background are graphic intensive apps, as video overlay and Dscaler can easily saturate the PCI and AGP bus.
Chiz
Couldn't just nef for my 2000th post, hope this helps 🙂