FAT or exFAT or NTFS

Solution 1:

FAT

Fat is definitely off the table since it only supports files up to 4GB. So you won't be able to transfer files over 4GB like you stated in your question.

exFAT

exFAT won't have this limit since it's capable of supporting files up to 16 exabytes (16.000.000 terabytes). It's an excellent format for your flash drives and/or external (not internal!) hard drives.

NFTS

NFTS is an alternative, but your Mac (starting from 10.3) can only read it. It won't be able to write data on the drive, unless you use some extra software and hacks, but some users have reported some instability and performance issues using NFTS on a Mac.

Windows/Mac

Windows 7 will read and write FAT, exFAT and NFTS without any problem. (It can even ReadyBoost from an exFat flash drive). Starting from Mac OS X 10.6.5, the OS supports reading from and writing to exFAT formatted drives.

Conslusion

I would go for the exFAT. It's fast, supports huge datafiles and both your Windows 7 and your Mac will be able to read/write to it.

Solution 2:

The only format that support all of your requirements is ExFAT. It is natively supported by Win7, Lion and Snow Leopard (from 10.6.5, I believe).

Solution 3:

I would actually recommend a 4th option - HFS+. I'm using Paragon HFS+ for Windows and its working very well. For $20 I am very happy with it and it definitely had advantages on the Mac side that you will not get with exFAT (TimeMachine, resizability, larger file sizes).

Solution 4:

I'd like to point out that exFAT is orders of magnitude slower on the mac than HFS+ or FAT32, especially when used on a spinning hard disk. It works well on solid state (ssd's or flash).