I've never heard of a monitor/video card that doesn't support an DVI-VGA convertion, but I can be wrong. I can tell from experience that even old and outdated Monitors will run on DVI through an adapter. I say this because when I bought a computer for my grandmother, I got her a 15'' LCD screen that was like, from the beginning of time - really crappy.
When I moved my X850XT from mine to hers, the monitor worked flawlessly with the adapter. But again, I'm no hardware expert, so I could be wrong. Maybe that's the reason you're not getting good information on this topic?
And I do agree that DX10 is, as of now, overkill. Last time I checked, the only cards on the market that had a DX10 support were the GeForce 8800 series. ATI's just a few tiny inches of making the R600 release, but they'll probably be as - or even more - expensive as the 8800s. So, the rule of the thumb is... get a Mobo with a PCIe 16x and a low-profile video card that suits your needs, especially if you're not doing a lot of heavy gaming. Just then, when you're ready to either go with Vista or play DX10-required games, get a DX10 compliant.
Heck, as far as I know, the only game out there that requires DX10 to work is Supreme Commander ( again, correct me if I'm wrong. It's been three weeks since I last checked the hardware scene, and since we're in a time of heavy transition... ), so you might not need it for a few years more.
And like other users suggested, don't go cheap on your power supply. The whole rig depends on it, and poor supply can cause pretty nasty stability issues and even smoke everything inside it. Try getting one with at least one 12v-Rail and 8-pin CPU connector, although, for the C2D, that's not required. And try getting one with some sort of cooling system. These new PSUs are hot as hell. Even more so if you're going 600W+.
But for some of the prices you're putting out there, you can get yourself a pretty nice PC with 1.2k euros. That comes to be what, around 1620 USD, considering the Euro at 1.3475? It's around what I put down on mine, if you take out the extended warranties, shipping, 19'' monitor and an OEM XP Pro copy. ( With free Vista upgrade
).
Just as a basis, here's what I'm running:
EVGA 680i A1 SLI Motherboard
Core2 Duo - E6400 @ 2.13 ghz
Patriot Extreme 2GB low latency @ 800mhz
Seagate 320GB HD + Maxtor 320GB HD @ 7200RPM
EVGA Nvidia GeForce 8800GTS
Samsung DVD +- R/RW
Zalman CNP9500 Cooler with Artic Silver 5 thermal compound.
And a few other thingies such as thermal monitor (useless, but looks cool), card-reader and 3 case-fans.
I'm planning on using EVGA's Step-Up program to trade my 8800GTS in for a GTX and just pay the difference. My friend at school has almost the exact same rig as I do, and he's getting almost 3dMark scores with 3k points over mine.