Lets look at this objectively.
Thread Title: Windows 7 and vista can't recognize my 1TB HDD only shows 465GB
First Line: hi ppl hope everthings good there, i have a seagate barracuda 7.200 with 1500GB
Problem: 465GB showing up.
There are 3 different sizes here, you've reported 2 different ones, and 2 Operating Systems reported another size. Do you know what size your drive is?
Sounds to me like you don't. If Disk Management in 2 operating systems thinks it is 465GB (about right for a 500GB drive) I bet it is a 500GB drive and not a 1TB or 1.5TB drive like you think.
Now maybe you could have 2 of 3 platters die, but I suspect that the drive wouldn't function inside Windows if that had happened. I also think Seagate uses 4 375GB platters rather than 3 500GB platters, so if that is the case, it wouldn't be possible to end up with 500GB.
Samsung does have a 3 platter @ 500GB each..
The only other possibility I can think of is a software limitation (unlikely to occur in Both OSes without you knowing, and impossible with a virgin install of the OS), or a hardware limitation of 500GB which is probably only possible in an older external enclosure (although I've heard many times of people running larger drives than the advertised capacity of the enclosure).