64-bit\66mhz vs 32-bit\66mhz

I'm putting together a file server. I am upgrading the house to gigabit so file transfers are faster. Now, I'm looking at 64/32 bit cards and wondering if I'll see a difference (my server mobo has 64-bit slots). My hard drives are all ata133 non-raid and on a 32-bit\66mhz ata controller - I can't afford a 64 bit ide controller. I'm not looking to max out gigabit, just get the best performance for the buck.

The 64-bit card is 30 bucks compaired to the cheap 10 dollar g-bit cards and I'd only need one for the server to the switch.

What are the benefits of going 64-bit/66mhz over 32-bit/66mhz? Would it be worth the extra $20?