Workstation Recommendations?

Long time, no write. Among other things, my aging R3000Z has been a huge factor in the lack of posts-it's now to the point where I simply don't trust it for anything more complicated than web surfing. Some days it seems barely capable of that-YouTube videos are a big no-no. As a result most of my work at home has ground to a complete halt, blog included.

Which brings me to today's topic-workstations! I've pretty much come to the conclusion that I'd like to go desktop this time around, but I'm looking for something with a lot of horsepower and a fairly long useful lifetime. Here's my short list of candidates, along with what I'm thinking about them right now.

Dell XPS 420
Strictly speaking, not a workstation, but I think it compares favourably with a nice Quad Core and I'm not enamoured of Dell's workstation line. I've never owned a Dell, and I'm a little leery of the build quality here. I do like the looks of this system (Wow-I never thought I'd say that about a Dell!), and I suppose I can always slap Linux on here alongside Vista.

Sun Ultra 24
This appears to be a fairly new system, or at least I don't remember seeing it until recently. I've been experimenting with an Ultra 60 for a few months now and I've been very impressed with Sun's build quality. Solaris seems to be a rock solid operating system, if a little dated visually; hardware compatibility is possibly an issue here as well. Of course as an x86 machine the Ultra 24 will handle Linux and Vista, but I don't know if I like the video card options here-NVS290 card seems to be a requirement in that you can add another video card but you can't opt for replacing the NVS290 instead.

Apple Mac Pro
I like the expandability and potential for customization here. I've heard the rumours that a refresh of the line is coming down the line in early 2008 (January maybe?), so it might be worth holding out for a while just to see. There is the issue of the "Apple Tax" here, although price-wise it competes favourably with other Xeon dual processor machines I've looked at so far. Video cards seem a little dated, though.

TuxBox FullTails
Boutique sellers like TuxBox offer a lot for the money, and I expect that the build quality here is quite good. I am a little leery of smaller outfits as unknowns in general, and the TuxBox site seems to be unavailable semi-frequently. They're a fairly new outfit I think, so it could just be growing pains for the company.

TuxBox LabCoat
Another nice TuxBox system, although AMD isn't my Number 1 choice for processors right now.

CyberPower
JNCS
Xi Computer
Thinkmate
Just some of the other boutique sellers I've looked at-no particular makes or models in mind.

If you think I should look at another system or run screaming into the hills away from one of the ones I've listed, let me know!