I just got back from the US less than 24hrs ago (hence the jet lag). I bought a logitech g15, a logitech mx620 cordless mouse, and 2 sets of 2x1gb Geil EvoOne RAM. All in original packaging, with the mouse and RAM being taken in my hand baggage. Got thru without so much as a second look. The only reason I couldn't get my new gfx card was that I had no cash left, nor did I have any space

.
Bought a mobo + samsung 206bw monitor from Malaysia in september 2007 - alongwith TONS of other shopping. Once again, no questions asked. Technically I have kept my electronic purchases under/around 25k, but they still never botheres to check.
Maybe I should carry a few k's of coke next time around.........hmmmm??
Jokes apart tho - the customs guys will NOT bother you a majority of the time. They are extremeley smart and know who to look for. Their primary aim is people who are looking to resell or are not carrying stuff for personal use. Of course, if you look/walk in scared or nervous, they'll pick up on this from a mile away and then all bets are off. Why would they turn down a chance to make a few extra bucks if they see a potential 'bakra' coming their way, eh?
As far as carrying a laptop goes, just make sure that whoever is carrying it for you is
familiar with the inner workings of a laptop, and with that particular machine if possible. About three years ago somebody in front of me got stopped because when he claimed that his laptop was for personal use and that he had in fact taken it from India before his trip, the customs guy took his laptop, started it up, and asked him to name which programs he had in there, as well name one file/document that he had personally saved. And since he wasn't prepared, they put the squeeze on him.
Other than that I personally have never experienced any sort of problem with these guys. There is always the chance that you can get one guy on and off day who's having a bad mood and is just out to get you, but there's nothing you can do about that anyway. Given that 9 outta ten times you're likely to get thru, it's a chance I'm willing to take.
Now to sleep for the next two days!!
*SNORE*