1. I see no difference in the performance as they are basically the same computer.
2. I've had good luck with Newegg as far as return policy for immediate defects but because it's an HP computer, you'll still have basic support from HP no matter where you buy it.
3. Most of the larger towers like the one you've shown should have an extra PCI slot for a third party audio card.
4. There are lots of custom shops and other brand name computer companies which might satisfy your needs. I can only suggest you check around.
Hope this helps.
Grif
I am about to buy an HP Z400 - either a FM045UT-PR2 directly from HP:
https://h71016.www7.hp.com/MiddleFrame.asp?page=config&ProductLineId=433&FamilyId=3005&BaseId=34511&jumpid=in_r2910_psg_080110_ws1/q110wssmartchoice/psgpromo/FM045UTPR2/heasmith&oi=E9CED&BEID=19701&SBLID=
or a FM045UT#ABA from newegg.com:
http://www.newegg.com/Product/Product.aspx?Item=N82E16883147546
1st question - aside from the inclusion of the monitor and computer/mouse (which I am not concerned with), what are the differences between these two computers in terms of performance? Are there any?
2nd question - are there any advantages to buying directly from HP? Obviously I would be better buying from newegg.com and purchasing the monitor separately (I would prefer a Samsung PX2370 over the monitor HP provides), but I want to know if there are any disadvantages to buying from a third party vendor (warranty, service, etc.).
3rd question - Can I install an aftermarket sound card that would provide an S/PDIF audio output from this computer? Apparently this is not a capability that the onboard soundcard has, or so HP advises me. I have an iDecco audio unit that I use to listen to music with and it allows S/PDIF audio input and does the D to A conversion onboard.
4th question - Should I be shopping somewhere else for this computer besides newegg.com?
This computer is going to be used (almost exclusively) for AutoCAD/BIM and high-end audio
Thanks so much for the help.

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