Grey Ninja - what are you using for you're PL2? (and more importantly how much did it cost?) I've been looking for a cheap surround system, and my PC could use a better card anyway.. might be able to kill two birds with one stone.
I'm using a homemade GC VGA cable, which I'd suggest is well worth the effort if your cube is all you want to connect to your monitor. The quality is absolutely the best you can get from a GameCube, but unfortunately I can't play a few games without switching to my 15" TV (from 1985). My cable, the same as the sort you'll find at goldenshop, will work just fine with an interlaced signal, but most monitors do not. If I understand correctly, the 480i 15khz signal is converted to a non-interlaced format, but it still runs at 15k, and very few monitors will accept a frequency lower than 31. I've seen one such cable attached to a projector (the results of which are marvelous) and I was suprised to see that it accepts both formats from the same signal and hardly hiccoughs when switched between the two.
By the way Scyth3r, what TV card do you use? I've had experience with two crappy cards, both from now defunct companies. needless to say the image quality was pretty bad, even my little TV can produce a better picture (and I can actually read the text it displays). it's been years since I've looked into those things though...
edit: I got my hertz wrong, monitors use 60 or 70 some-odd, interlaced signals are around 31. I think... I'll just shut up
Oh, one last thing. From looking at this VB50 HRTV, it doesn't have the ports you need for a progressive signal from your cube (you want progressive, you really do). sounds terrific for any older systems, and those few games that won't use progressive (there all third party btw).