i just recently bought a computer for my sister. charged to a credit card in Texas, sent to an address in New Jersey. dont know which state they use for sales tax purposes, but we didnt get charged any tax.
edit: BTW, just had a good experience with HP customer service. my sister just received her computer about 3 days ago. she's pretty computer illiterate and couldnt determine whether or not it had a floppy drive. today HP called her - they somehow knew that they forgot to include the floppy drive, so they are sending her a free $50 gift certificate and a 64mb USB key drive. $100 worth of stuff for a $15 item seems like a darn good deal to me, and we hadn't even mentioned it to them...