The specifications for LabVIEW 8.0 state that only Windows 2000 and XP are supported.
During development, the versions at the time of third-party providers were tested with LabVIEW's source control integration. SourceSafe 6.0 was the released version so that is what was used. SourceSafe 2005 was not released at the time but a cursory test of it with LabVIEW showed that it worked fine (2005 seems to be a polished version of 6.0 with some new functionality, but essentially the same core).
Regarding support of third-party source control providers. The LabVIEW interface is as generic as possible to accommodate as many providers are possible. Since there is no way through LabVIEW to enforce functionality, some providers may have behavior that is not expected and could cause problems. This is even true between version releases of a provider. That is why while the integration should work as advertised, complete functionality cannot be guaranteed.
George M
National Instruments