Small Business Server 2003 + Exchange Service Packs

I have a Windows 2003 SBS server that I have inherited and I need to apply service packs. I understand that service packs need to be applied in a specifc order on sbs. My understanding was that you would apply windows 2003 SP1 then Exchange SP1 and finally SBS SP1. However I have noticed that when I go into Exchange system manager the verison number is listed as Version 6.5 (Build 7226.6:Service Pack 1)
Does this mean that someone has already applied SP1 to exchange. Now I am a bit reluctant to apply SBS SP1 to the OS as the service packs may have been applied in the wrong order? Has anyone come across this before or know if i apply the SBS service packs when I install Exchange sp1 it would tell me it is already installed?

Thanks