64-bit WEP Is Better Than 128-bit WEP

I am setting up a new wireless network tonight and enabling WEP encryption on my cheapo router.

When using WEP, you have a choice of key strengths: 64-bit and 128-bit

In the past I always chose 128-bit encryption because it is "stronger".  This time I went with 64-bit, and here is my reasoning:

All I care about is keeping away casual snoopers and freeloaders from my wireless connection.  I live in a dense part of Boston and can pick up 10+ wireless signals from my apartment at any given time, so this is likely.  Anybody with skills who seriously wanted to penetrate my network could do so with either key strength. Cracking the 128-bit encryption isn't much more of a hurdle than the 64-bit, so why bother?

Why slow down all your packets, waste your batteries (decryption is processor hungry and therefore laptop/battery hungry), and have a longer key to keep track of, when the added security it gives you doesn't exist?

(note: If I wanted to block anything more than casual usage, I wouldn't use WEP in the first place)