How do i move a 5gb file to my windows partition?

Use PuTTY on the Windows Box and copy it using scp:

scp user@mac.local:/path/to/file .

"user" is zou short mac user name
"mac.local" is the hostname of zour mac in the network
"PuTTY" can be found with Google

 

This is probably because your drives are fat32
http://en.wikipedia.org/wiki/File_Allocation_Table

you need an ntfs partition to do this.

 

Boot from Windows, open the Mac drive in My Computer, then using the read only drivers installed with Boot Camp, navigate to the file and copy it to your Windows partition.

 

If you are using Windows 7 on your Bootcamp, you can format the thumb drive in exFat and that can be read and written to by both Windows and OSX and has large file support (like HFS+ and NTFS have).