My problems started when I set up an exploratory domain controller at home. During that process, I changed the name of my laptop, from 'erisia' to 'erisia-laptop', and this resulted in me losing my admin account on SQL Server 2005 on my laptop. SQL Server seems to store the machine name as part of the user name, so now my local admin account is 'erisia-laptop\brady', which SQL server didn't recognise.
I thought I'd cut my losses and just re-install SQL 2005, but the first install was aborted, so I tried a complete uninstall, followed by the new install. The latter didn't work while the former worked way too well.
Now every attempt at installing SQL Server 2005 SP2 on my laptop running XP SP3 ends in sadness, with MSXML6 being the cause, because it won't install on this OS version. WTF? Does anyone know what I can do to get SQL 2005 installed? It's the only full admin DB tool I have. SQL 2008 Express that installed with VS 2010 Beta 2 doesn't allow much server admin.