System Center Operations Manager 2007 will NOT be available via MSDN or TechNet download. An evaluation version of OpsMgr 2007 is a currently available for immediate download. If you're interested in purchasing the product, you can upgrade from evaluation to RTM using a tool that comes with the RTM version (on the DVD). The RTM bits are available for download on MVLS now, and will be in the May VL media kits. Upgrading from Eval to RTM should not have any impact on the client machines.
Note that this is the case for English only, as the other languages won’t have the eval upgrade utility included until a later date (Summer 07)
Download the System Center Operations Manager 2007 evaluation (~280 MB):
http://www.microsoft.com/technet/prodtechnol/eval/scom/default.mspx