A - yes. you should probably un-install WAMP if you plan to use XAMPP - they are redundant BUT - you should un-install any items you had running as Service FIRST - i.e. htppd.exe (Apache) and MySQL (that's a WAMP thingy, so I don't know where they handle that, I haven't used it in a long time )
how to check for MySQL as service (or Apache):
Computer > Manage > Services
MySQL or mysql - right clcik to get its properties, then look at 'path to exectable' if it show it in WAMP's folder that is proabably the issue or Apache 2.2 or httpd.exe
B - the UAC issue is circumvented by using 'Run as Administrator' AFAIK. I don't normally work on Vista machine, but I'll check. There is another workaround that obviates all that - when you run XAMPP to develop on - use the administrator account.
Use the CMD prompt with 'run as administrator'
then type 'net user administrator /active:yes'
logout or restart and you get an option to logon as administratorhttp://www.howtogeek.com/howto/windows- ... ows-vista/
C. - the fact the file is not there probably means that MySQL never got to launch at all.