Well, I can give you a few tips to speed up performance,
but most of mine are reliant on purchasing top of the line hardware.
1) One of the area's you might want to check out is the manual for the "Touch Mixxa".
Greg had some good general tips in here for speeding up video streaming. Besides, you may fall in love with Mixxa, it's very cool.
2) Have your textures on an internal drive that (during performance) is not being used for anything else (not running Touch, or the operating system). Perhaps even spread the textures out over a few drives? Then you could go with a 10,000 RPM drives as well... although some of the Solid State hard drives are about the same speed now, and run much cooler and are more far more reliable. I go with solid state whenever possible, less data can be stored, and more $, but small, cool, and great for traveling. The military drop these out of airplanes.
3) This is one of the most important tips for hardware! Get a single board Nvidia graphics card with loads of "texture/video memory". I recommend the Nvidia Geforce GTX 285, the EVGA FTW edition is particularly nice http://www.evga.com/products/moreInfo.a ... s%20Family
Stay away from cards with two PCB (Printable Circuit Boards) for Touch use (such as the standard edition of the Geforce GTX 295, and the nvidia 9800 gx2. With these cards, touch can only really recognize one of the two PCB's. Forget SLI (multiple graphics cards in one machine) with Touch, at least for now... unless something has changed that I don't know about.
Also there is a new EVGA Geforce GTX 295 co-op edition, which has two GPU's on a single PCB. I just found out that this card functions by implementing SLI technology, so I don't think Touch can leverage both GPU's. This one needs to be answered by the Derivative folk.
4) Other than that, a 64 bit operating system, lot's of Ram, fast processor and sweet motherboard.
CPU: intel i7 quad core with large cache.
Mother Board: Nvidia X58
Ram: 8 gig of DDR3. You may want to go with less than 8, because single layered ram is
faster than dual layered. I recommend OCZ ram.
operating system: 64 bit operating systems are the only ones that can read more than 4 GB of ram. There is Vista 64, which some people loath. There is also the hard to find XP 64, which is great, but is no longer supported by Microsoft. Fairly soon Windows 7 will come out, and this should be the best answer, or at least one hopes.
Hope that helps.