If I were you, I'd do yourself a favor and shower.

I was reading a blog today and came across a sentence that the author felt ambiguous about (at least, so I infer, based on his writing):

If I were you (don't worry, I'm not), I'd do yourself (myself?) a favor download it

It's clear that the author was joking (based on the first parenthetical), but it doesn't seem entirely infelicitous to use either one.  So I did a little Google research, and searched some strings, the results of which are below:

• 47 hits: "you i'd do myself a favor" or "you i would do myself a favor"
• 24 hits: "you i'd do yourself a favor" or "you i would do yourself a favor"

While it's clear that people prefer "myself" in these situations, it's also clear that it is a grammatical utterance to say something like "If I were you, I'd do yourself a favor..."  But I wonder if there are any meaning differences, or other ways in which the choice of  "myself"/"yourself" affects the structure/binding.

What are your judgments? Do you have any thoughts about the distinction between the sentence with "myself" and the sentence with "yourself"?