I recently bought a Fireface UFX and a new computer and am in the process of getting them set up.  The computer has the following components: Asus P8P67 Deluxe REV 3 LGA 1155, i7 2600K 3.4Ghz, Windows 7 SP1 Home Premium 64 bit, Mushkin 8GB DDR3, NVIDIA Quadro FX580, LG BH12LS35 Blu-ray writer, WD Velociraptor 450 GB SATA 3 - 6Gb/s 10,000 RPM for OS, one WD Caviar Black 1TB SATA 3 6Gb/s 7,200 RPM for audio, and one for sample library, Corsair Pro Gold AX750 power, Corsair Cooling Hydro H70. I have purchased Pro Tools 9, as well as the Pro Tools Instrument Expansion Kit, but haven't installed them yet.

The tech person in the Pro Audio section of the store where I purchased the UFX maintained that I would get better performance using a FW connection to the computer as opposed to USB2. However, the UFX manual (sections 32.3 and 32.4) seems to imply that the bandwidth and performance of USB may be more robust than FW.

I am planning to purchase an external hard drive to use for backup (likely a 2 TB, USB3 hard drive). I noted that the Pro Tools web site indicates that it could be problematic if your audio interface is connected through USB when you also have an external hard drive connected through USB. However, they did not specify if that meant using an external hard drive for active audio files, or just to be used as backup (as I will be doing).

Some advice on this matter would be appreciated.