Ordering integration tests with NUnit for test automation

I'm writing a test automation framework using the below technologies:

Selenium Web Driver
NUnit
cSharp
Visual Studio

In Java I can use the testng.xml file to group tests together (test suites) and have them run in the order they are listed.

Now that I'm using cSharp with NUnit, creating test suites with tests that run in order have not been as straight forward.

Right now I'm using the order attribute at the test fixture level, and grouping tests using test categories. This was working fine until test # 5 needs to be run in a different order with another test suite.

Has anyone had a similar experience and could offer any insight on this type of issue?

Thanks!