This Dell XPS is pretty loud. I knew it wouldn't be the best, but I didn't expect it to be that bad. It might be OK in a regular office environment, but in my home office, where there is no much noise around, the computer is the loudest piece of equipment.
The most annoying thing is the video card. By the way, its brand is "Pegatron" - I've never heard of this name before. Apparently that's a part of ASUS company, which split several years ago. This video card has a very cheap small and extremely noisy fan. I was tired of that noise, and after I got a permission from Mozilla IT guy to modify my PC (as long as I don't break it :)), I started from that annoying little VGA cooler.
I had a pretty big and heavy copper VGA cooler, which I bought several years ago for my HTPC. Since then I upgraded the motherboard in the HTPC, to the one with integrated nVidia 8200, so this VGA cooler was not used. Luckily its mounting screws could be adjusted to fit the holes on the this ATI HD5670, and the radiator did not touch any parts, so I installed it. There was one problem though - the original fan on the VGA cooler was connected to the card itself, and that connector was too small for a 3rd-party cooler fan. Dell motherboard doesn't have any more fan connectors, so I had to be inventive - I cut two pieces from a paper clip, ground them down a bit, inserted into a floppy drive power cable, and connected the fan to that improvised power source. It worked! I put everything together, and now my computer is noticeably quieter without that constant buzz from the video card.