2^32=4,294,967,296 or 4 gigabyte
2^64=1.84467441 x 10^19 or 18 pentillion (move the decimal point 19 places to the right) 18,446,744,100,000,000,000
A terabyte is 1024 gigabytes or 2^40= 1.099 x 10^12 =1,099,511,627,776
64 bit is MUCH more than a terabyte
Yea, I "think" its 16 "Exa"bytes, but, I don't know if there is a software limit in there somewhere where the OS will actually hit a limit before it hits the theoretical limit? I've could have sworn that I've seen a memory max for 64bit windows, and it was a lot less than exabytes.
Point is, with 64bit, you have the ability to use more memory then you can ever practically buy and put into a machine. Most machines won't be able to install more than 16Gigs at best, at least today. Again in the future, it will go up, I won't be surprised if someone posts a machine on sale today that does more than the 16Gigs I said.
Yes, Bill Gates said the same thing about 640k base/1mb extended memory years ago, that was laughably wrong, and this may turn out to be the same. But its safe to say for the life of the next computer you buy, you won't be able to exceed any memory limit of 64bit windows. While 32bit, in most cases you will hit a limit with most new computers. You still have some time before having to worry about it with 64bit.
I avoid Sony because of past experiences, NOT laptops, and a lot of their company policies for things other than laptops turn me off. I've never heard anything bad, actually a lot of good about Sony.
HP, I had a bad experience, others do NOT, if you google some of their models you'll see lots of people complaining of problems with the same thing for that model. e.g. bad power connectors in the laptop, NOT power supply, making it expensive to repair, failing motherboards which cost 75%-90% the new price of the laptop to replace, etc.. I think its fair to say that HP has some good models and some more unreliable models, which I haven't run into with Asus, so I stick with Asus.