I've always found it's better just to pay the extra 50% and get a better system. There seems to always be a sweet spot for computer hardware between price and performance. Pay more, you're just getting ripped off for minimum performance increases, pay less and your just saving a couple bucks now for limited use and often stability problems in the future. This is especially the case with motherboards and power supplies (often the most overlooked components).
What good is the 20$ you saved on the board when it dies on you? Even if the manufacturer has a decent warranty on it, your computer is out of service while it's replaced? As for the performance/price level, look at ram right now, you can buy 128mb pc133 sd-ram for 45$CDN or 256mb pc2100 ddr 266Mhz for 65$CDN (Canadian dollar is currently at about 0.65USD). Not only will the latter result in a major performance increase, but it will also be supported by newer motherboards for a longer period of time, all for 20$ extra. Processors are the same way, a 1.3Ghz Duron only costs 70$CDN (XP 1800+ around 120$CDN) it's definately worth it at these prices IMHO.
As for integrated systems video card/board/cpu, I personally see many problems with them. One being that I've traditionally found them to be very low quality, and the other being it's harder to upgrade them and when one part goes down it takes the entire system with it. Support by various operating systems can also be a problem.
I also wouldn't buy parts from a place called IDOT computers. I keep thinking it's missing an 'i' every time I see it 8^) </cheapshot>. Interesting discussion though, even if this is a Perl site.