I am wanting to buy the MBP (decided to just do the 2.4ghz) and would like to get the 320gb hard drive. do they have these in store or do i have to order them online?
Probably not, Apple stores usually only carry stock models. You could always try giving them a call to check for sure. Your best bet is to buy from the online store.
Just so you know, for the same price as upgrading to the 320gb drive from Apple, you can purchase one separately and keep the old 250gb:
As long as it is done without doing any damage to the computer your warranty is fine. Download and read the owners manual from Apple's site and you will find instructions for upgrading the HD and RAM. Both are considered owner serviceable parts.
If you do the HD yourself I'd recommend buying from OWC, they have excellent pre and post sales service and even provide videos for installation. They're link is:
Just get the stock model and then buy the hard drive from another place for much cheaper and install it yourself. Plus, you can use the 250GB for backups or storage.
I am wanting to buy the MBP (decided to just do the 2.4ghz) and would like to get the 320gb hard drive. do they have these in store or do i have to order them online?
why would you waste your money and/or time upgrading from a 250GB to a 320GB? Thats only 70GB difference. If you are going to upgrade, first do it yourself, the stock 250GB would be a nice backup drive inside a USB enclosure and second buy a 500GB or bigger OR SSD.