Ubuntu 12.04 (X64bit) 32 Gigs of ram
2 Virtual machines running
1 2011 Small Business Server ( Currently 10gb)
1 2008 R2 Server ( 6gb ram)
We just updated our server to the max our board can handle the boxes were previously configure with 6gb each
Anything we allocated to the SMBS over 10gb it would crash the virtual box when configuring services.