The reason I got the PowerEdge Dell server is that they are very cheap right now. You get a very high quality case and chassis that's a dream when it comes to upgrading just about anything.
I think when you go w/socket 478, you consciously put yourself at a dead end, anyway. I doubt there will be another socket 478 chipset beyond the 475P, and I'm still unclear about whether the high GHz PIV scheduled for later this year are even on that socket. I don't think they could be, because of some temperature anomalies people have noticed when pushing this architecture to the 4.0 GHz that Intel is talking about before the end of this year.
It's a very quiet setup, too. The fan pulls air from the shrouded heatsink and out the back of the case, and it's replaced by cool air sucked in through that weird looking front. That weird looking front hids a stereo headphone jack and two USB ports, by the way. LOL... Nobody seems to know that or if they do, they're not talking 'bout it.
There are also some undocumented, supported items on the mainboard. SATA works on this mainboard, for example. You can also connect extra CPU fans if you go over 3.2 GHz, but I found this out by trying...it's not mentioned in the documentation anywhere.
You wouldn't expect this of a server, but it also supports AGP 8X, and since it's an Intel chipset everything's automatic. No problems or special drivers.
I knew there wasn't going to be an easy way to overclock, which fact is responsible for my choice of the 3.0 GHz PIV HT as the "likely sweet spot" instead of the 2.8 or 2.6. You can get a 3.0 GHz with a decent quality heat sink and fan (I got this just in case it started overheating w/the Dell OEM, but it doesn't) for $270.
I dunno. I take your point, but since it looks like the PowerEdge 400SC is all over the place for $400 - $450, I think it's a very good place to start building a system that's going to see heavy use.