On my desktop(Win7) I had originally installed SQL 2008 using SQL Auth mode with a newly created user. Well later when creating some sample databases in a unique Win directory I kept running into Windows permissions errors. Even after creating a new Windows users to match my SQL user name I was still getting permission errors. Pain in the rear because the SQL errors are hard to decipher. So I tried to find a way around this, just switch to using WinAuth but I couldnt get it to ever work. So I eventually wound up just re-installing SQL 2008 after having to manually going thru and uninstalling about 10 SQL programs. There were issues when I got to the ServerConfig option where you specify a username for each SQL service, ugh. Like be sure you know what your doing here! In later releases MS seems to fill in a default different username for each SQL service but in 2008 these fields are blank. Finally got around it and the issues resulting from this.
During this time I also installed SQL 2012 on my laptop(win8). Which for the most part went smooth then I realized the next day I had installed while being logged in on a non-admin account. I had given permissions during installation but the next day when logging in via SSMS the WinAuth was trying to use my non-admin user and for some reason SSMS has the userName boxed greyed out during login, why is that? Also the SQL Browser service was in the “Disabled” state, ugh again.
What is sort of strange to me is just trying to do a default installation I felt would be a lot more simpler and error-free. As of this moment everything appears to be working but I am sure there are a ton more “gotchas” waiting to be discovered.