Leaving the phone at 1.1.1 is fine for the American Cousins - the telephone numbers and stuff are all american - but there are some fixes (stevonw here is one of us even if he is scots, and has the recipe I believe)
Also I like the foreign keyboard options in 1.1.2 and I like my pc not nagging me about upgrading to the latest version.
You'll need to modify that guide because you're not unlocking. Basically:
Get phone in recovery mode
plug into iTunes and force a recovery to 1.1.1 mode
open some tool like the touchfree 1.1.2 jailbreak to get the thing out of recovery
do the *#307* / jailbreakme.com malarkey (this is fun after a while I have done two at once on with each hand)
Install Oktoprep, Then start all over again Updating this time to 1.1.2
Jailbreak again with the touchfree doofer
That's it! - 20 mins tops.