Need new PC. My Dell Optiplex 480 is too old & getting slow.

I need to replace my desktop PC tower with a new one. Not sure what make or model is best for me. This won't be short because I'm going to give details so someone might be able to point out the best one for the projects I'm doing here at home. I have looked at a few, HP, Dell, Lenovo, Asus, Acer, eMachines, and I'm still leaning towards Dell Inspiron 3670 since it's a dual drive system. Not sure if this is best or what brand to choose; although I've read that Dell is on the outs due to poor quality and increasing reliability issues from the some of the articles on various review sites. This is what I'm redoing: Uploading and remastering (about 20% need it) my music collection that includes 1,900+ albums, around 345 45 rpm's, 295 cassettes, 16 reel-to-reels, 300 CD's. I also want to upload my 200+ VHS.tapes. Reasons: Most of my music; other than the CD's are first printing with different tracks than currently available (about 60% is unavailable for replacement) and there are only 25 duplicates across all titles. The VHS are in perfect condition and the VHS deck has excellent picture quality, plus they're all paid for so I can't see any sound reason to buy a new DVD copy (200 X $8 avg = Way too much money). I have a large $550 CAD/CAM software program for my auto hobby (building my mid-engine sports car) and do custom car designs for a few friends and a $450 program for music remastering; which both use a lot of RAM when in use for graphics and processing. Here are issues I have found that are making my choices harder: mouse, keyboard, printer, 5.1 surround system, & MagicJack are all 2.0 USB plug-ins so the tower needs at Least 6 - 2.0 USB ports. The monitor, 24" Dell flat screen I will upgrade w/touch capabilities after the new tower, is a serial port and my alt monitor is my 47" Toshiba TV that I connect w/HDMI and internet connection has to be hardwired via Ethernet (work requirement security protocol). I really don't want to spend $850 if possible. From what I "think" i need, a config close to the Dell 3670 might be OK but I'm not sure. I do know I'd need something expandable/upgradeable since I don't like spending money wastefully. As I said, it's long but I figured the more someone knows what I'd be doing with the desktop, the better it might help some direct me to the right tower. Also, the desktop does not get shut off except once a month for 8 hours after normal virus software and system scans/updates because my MagicJack is my phone since I work 6 days/wk - 12hr/day on the railroad so I have no need for a cell.