Cliff,
you can do that, but that would not be my personal approach.
Note: using robots.txt to try to handle problems in an application is not its intent. the application problems need resolved.
you likely have some issues of possible duplicated content, which can result in penalization by google.
if google is your only concern, use the nofollow robots metatag in your myaccount pages.
you should note that only some bots support the nofollow robots metatag.
also - there may be some URL issues with googlebot regarding sessions and cookies. I have very solid browsers support in my BVC2004. I do not have time now to try to build out browsers definitions for BVC5 and given the price, I doubt they are included.
now that the adsense bot seems to be working with regular google results, the nightmare swells.
cliff, depending on the URL structure, you may want to consider killing the unrewritten links with something like
User-agent: *
Disallow: /*categoryid=
Disallow: /*affid=
As a word of caution for those considering upgrading from one cart app to another - An unplanned change to your sites URL scheme can result in significant drops in traffic. These sort of things require careful strategy and planning.
Scott Mech
[email protected]