First things first.. the pre-reqs:
A database! – SQL 2008 R2, but which version..? – this should help, SQL 2008 R2 Features and Comparisons http://msdn.microsoft.com/en-us/library/cc645993(SQL.105).aspx
this was later commented on in http://social.technet.microsoft.com/Forums/en-US/systemcenteressentials/thread/0b8ecaae-19ce-43f5-b505-71dd7fb2d6e4/?prof=required, and the comment was ‘unfinished post!’ – there’re right I really should have finished this, but to answer the question Is SQL Express 2008 R2 supported with SCE2010? – I’d say a no and a yes..
SQL 2008 R2 does work with SCE2010 although I don’t know about Express edition… We have our SystemCenterEssentials dB on another host that happens to be a SQL Enterprise Edition box but as said it is holding the SCE dB (amongst others)
Reuben Cook CCNA, CCNP, MCSE, MCP+I, TS: Mobile, CfgMgr, OpsMgr, Virtualisation, SBS2008