Esxi 5 - Single Disk or Multiple VDisk for SBS2011?

Hi, Excuse my lack of understanding.  I am still very confused over best method to setup my Virtual Server an type of Disk Provisioning. I have read a lot but most "read me's" see to be based on larger "Enterprise" setups etc.   There doesn't seem to be much on "Best Practices" for small business (Single Servers).

OS: SBS2011

Hardware: ML350G6 with 3X300GB SAS 10K drives (Raid 10)

Total available Disk Space: 600GB

Proposed Backup Location: ReadyNas Ultra2 with 1GB

I was thinking of
C:\100GB for OS, D:\100GB for Apps (Exchange) and E:\100Gb for Users Data

Should I be creating "One Single" Virtual Disk of 300GB and then Partioning within SBS2011

OR

Create "Multiple" Virtual Disks for each (C D & E)

ALSO.  When I create the new VM what is to Best type of Provisioning to apply, Thin Thick etc?

Suggestions would be very welcome.