Yeap, smaller USB seems to work better, so if you have a 256-512 you should be golden.
1-2GB generally work as well, most issues are with 4-8GB or larger.
If you end up not having a USB that works, and you do not have a floppy or a spare hard drive you can create a FAT32 partition on, I can create a bootable CD for you with the BIOS on it.