No it will not change anything on your account
If you UPGRADE, your old account will have all the Architect Edition goodies, and a month of playtime added. If you CREATE, you'll get a second account - your old one will remain, but won't have the Super Booster selection or month of play; those will go to the new account.
Unless you want to run two simultaneous accounts (and pay monthly fees for both), it's generally recommended to UPGRADE your existing account. All your stuff will remain.
http://www.fimfiction.net/story/36641/My-Little-Exalt
Cool. Thanks for the info.
You can add all the boxed sets you want, one of each, and all they'll do is increase the time you've got, or add their individual goodies to your existing account. There is no difference between any playable accounts with the exception of what perk goodies such as costume parts and the odd power.
Please read my FEAR/Portal/HalfLife Fan Fiction!
Repurposed
This is probably a really dumb question (and I'm not sure if I'm even asking in the right place) but....
I originally opened my account with CoH Collector's Edition. I'm considering getting the Architect Edition but don't know what will happen to my old account. If I register a new version of the game, will all my old characters and stuff get wiped out?