Yeah, bring accessories, attachments and media. But not all the main stuff.
I wouldn't go the route of trusting transformers. If it were my stuff, this is what I would do:
2 desktop computers - CPUs only (not screens) and ONLY if they are marked for dual voltage. Later models should be, almost all latops are.
color printer - probably not; check for dual voltage...but I don't think they come that way unless they are laptop-related. Paper size is different and some American models might not "adjust" to European paper size. Oh, they may physically adjust, but the software inside might always default to "letter" and this can be a real pain/extra step everytime you want to print
scanner - I brought my scanner, no probs. But, it was dual voltage.
sewing machine - I brought my sewing machine only for sentiment reasons. I think I can have this altered by removing the motor and replacing it with another, but for now she just sits in the corner. Heck, it's a 1955 Necchi Super Nova!
(aside: my mother-in-law had the same model, only mine's cabineted and hers is portable. She loaned me hers and it still purrs after almost 50 years.)
serger machine - I would guess it would be the same answer as the sewing machine
TV w/ built-in DVD & VHS - ditch the TV, bring all the tapes and DVDs. You can get multi-region and NTSC/PAL players, and the prices are not bad. And, you'll want to buy tapes/DVDs over here; might as well have something that plays them all
(aside: you might also want to consider the fact the UK government is phasing out analog and trying to force everyone to go digital by the year 2010...that will mean buying a new set anyway.)
PDA charger - mine is dual voltage, so no problem. I think they purposely make all these travel-able. Just like all my camera chargers.
BTW...one thing about having US appliances that are dual voltage...say computers with peripherals that are also dual voltage. You don't have to get a US->UK adapter for all of them. Bring a US powerstrip (or multiway), plug all your US gadgets in that, then use one US->UK adapter to plug the power strip into one outlet...assuming you're not overloading it!
Oh, and the reason for no TVs or printers is that the frequency is different. You could get the electrics to work if you use a transformer, but the picture won't play properly.