I was able to raise a SuSe Linux 10.2 64-bit server and get Domino, Mail Security for Domino MPE 3.2.7 and Scan Engine 5.2.5 to all run at the same time with 512Mb of RAM. This is just proof of concept but for a small business that has limited resource this coule be valuable information.
The trick is installing Mail Security for Domino MPE first and the installing Scan Engine. Since they both use Java Liveupdate, you need to have Scan Engine be the most recent Java Liveupdate install which will be JLU 3.0. SMS will be able to use it still since it appears to be backwards compatible.