My computer is quite noisy. What is the best way of putting it in a different room? Right now I have two HD monitors and a usb audio interface, but I'd like to be future proof.
First, run some routine maintenance on your computer. If it's making some serious ticks, whirs and clicks there may be a bigger problem. If it sounds like a small turbine engine every time you boot up, open up the case and give it a good once over with a can (or two) of compressed air. Be sure to hit the fans, they're typically very noisy culprits. If the noises persist try hunting down any lose cabling that may be vibrating against the case. If it still ticks and clicks, it may be time to backup the discs and replace them. Ticking drives are 3.5" timebombs that are ready to go off at the most inopportune moment.
Having said that, if it's up to snuff and is just a distracting whine in the room, almost every place that I've worked in has used some variety of Gefen extenders. They allow you to make huge runs (200+ feet) for HDMI, DVI, S/PDIF, USB, Firewire, etc. using cat5/5e/6 cable. They're not cheap, but they're great little boxes that get the job done.
I've thought about that very much before too, but for me I found that just making it silent was much easier and more safe.
To make it completely silent I got meself an aluminum alloy chassis with internal padding (doesn't resonate at all), noiseless Seagate Barracuda discs (only ever use 2 in the same computer for the sake of noise and vibrations), a passive PSU, and passive graphics- and video-cards.
It wasn't even what much more expensive than non-silent stuff, just a little less powerful in areas where I, as a sound designer and audio engineer, don't need that much juice anyway, mostly the graphic interface!
IF the distance you're running is under 30 feet, then you try getting really good quality extender cables. I currently run about 30 feet from my "machine room" (really just a large closet) with just hi-quality extender USB and DVI cables. Make sure you spend a few bucks on them, don't use the el-cheapo stuff. Over that point you should consider in investing in the Extenders Steve mentioned. You could also consider isolation racks... we've had good luck with the Middle Atlantic stuff: http://www.middleatlantic.com/studio/ec/ecracks.htm. An option if putting the machine in another room is problematic for one reason or another.