Here’s basic thoughts about bringing electronics from the US to the UK. I’m not an expert on any of this but here’re things that worked for us.

General: We brought a voltage converter, but it’s sitting in a closet because in the end it’s easier to set things up so that they don’t need it. So it only gets used when visitors come. Beware that most voltage converters will not work for electronics anyway (if you read their instructions)–we blew a fuse the first time we tried to use it with our monitor, which turned out to have an internal voltage converter and didn’t need it anyway. Also, we brought a US power strip and tried to plug it in through one plug adapter, and then let stuff run off of it at 220, but it just blew out the fuse, so I would expect to just buy UK power strips and get individual plug adaptors.

Computers: In general I think it’s good to bring over any computer equipment that you can since prices for those sorts of things seem to be almost double than the cost in the US. Fortunately, most computers, monitors, etc. can take either 110 (as US) or 220 (as Europe) volts. So all you would have to buy a plug converter (versus a voltage converter). For a box computer, we just had to flip a voltage switch near where the power plug was to tell it 220 vs 110. As a side note, someone recommended just bringing our hard drive over and buying a new system here and adding the old HD to it to save on shipping expenses. But with computers being so much more expensive we just shipped it by USPS surface, which as I understand doesn’t exist any more (see here).

TV related: The US runs on the ‘NTSC’ standard, and Europe runs on ‘PAL’. Along with that, most TV related equipment here connects to one another with a ‘scart’ cord (instead of coax cable).
Gaming Systems (Playstations, etc.):From what I hear in the olden days (like 2+ years ago) that Playstations, etc. from the US wouldn’t even work on a UK TV set–I think primarily because US game systems didn’t have a scart connection. However, we were happy that our TV (basically the cheapest 20″ that we could find) came with the AV cord slots (the red, yellow, white plugs), and our US PS2 plays just fine here on this TV. However, PAL (i.e., European) games will NOT work on the NTSC PS2 unless you get a mod chip or something to unlock the system. We haven’t fooled with it. Also, the PS2 can run on 220 volts, so only need a plug converter.
DVDs: DVDs around the world all have a region code (US is region 1, Europe 2, etc.). So for a standard DVD player you get here in Europe, it shouldn’t play US region 1 DVDs. However, this problem can be easily taken care of through a couple of options: 1) Bring a gaming system from the US that plays DVDs (e.g., PS2, etc.) 2) Find a DVD player here that had decoding instructions on the internet that removes it’s region restrictions. Since we’ve got a PS2 (so option #1), we bought the cheapest UK player that we could find. It turns out that it plays about 1/3 of our US DVDs on its own, but we found a hack on the internet so it’s now region free.  Your computer will also switch between regions, but I’ve heard that you can only switch 5 times (with Win XP, at least), and then it locks into whatever your last choice was, so not really a good way to go. However, we’ve found that VLC Media Player works (freeware) will play DVDs from multiple regions without having to switch.

Misc. Electronics: There could be a random assortment of things you might bring. For instance we brought our Vonage router and a wireless modem (but remember that in Durham there is only DSL, so a cable modem isn’t worth bringing). They both run on 9.6 or 12 volts or something like that. You can buy replacement electrical plugs here that convert from a 220v UK plug to the little round plug that goes into the back of those for about £9 to £10, and I thought that has been the best option for those. The plug you buy has 7 or 8 different size adapters, so one of them will fit into what you’ve got.

Landlines: The UK phone lines are set up with two types of phone cords. One is exactly like the US, and the other is flatter. You can buy an adapter that switches between the two for a couple of £’s. I think it’s actually illegal to use foreign cordless phones in the UK if you were thinking of bringing yours.
Mobiles (aka cell phones): If you have a 3 band GSM phone it should work fine here. A quad-band GSM phone will definitely work with no troubles. You just need to get the phone unlocked, which will probably be cheaper and easier to do in the US. On a trip over we used our Nokia phone (the cheapest that you could get free in the US) without any troubles–I’m pretty sure it was a 3 band. Most people just use pay-as-you-go sims b/c 1) it’s hard to get set up on a monthly plan b/c no credit history and 2) since the pace of life is slower it’s cheaper to pay by the minute than to have unused monthly minutes. See also the more extensive thoughts on this of a recent addition to Durham’s phd family.

Small Appliances: We didn’t bring any, but anything with a motor will probably have trouble working because they use different Hertz rating. In the US it is 60 or something, and 50 in the UK. This relates to cycles, so motors won’t run as fast or something. Anyhow, unless you’re shipping a whole load over, I wouldn’t recommend wasting luggage space and weight for things like this.