This is close, but it is a fake.
This is NOT the genuine version of Vista x64 RTM SP1.
See the following article as posted in MyDigitalLife
Vista SP1 RC Refresh 2 6001.18000.080118-1840 Standalone Offline Install Package BT Download » My Digital Life
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Windows Vista SP1 RC Refresh 2 is probably the closet version to the RTM release of Service Pack 1 for Vista. There even many forums and blogs that dubbed Vista SP1 RC Refresh 2 with build number 6001.18000.080118-1840 as the RTM version, mainly due to the fact that Vista Service Pack 1 is now officially called only ?Service Pack 1?, without version number, and the desktop does not carry and plant with ?Evaluation Copy? watermark anymore.
However, Microsoft has not officially announced (until 2/4/08) the release of Vista SP1 RTM edition, and the documentation comes together with 6.0.6001.18000 (more detail 6001.18000.080118-1840) build version of SP1
has clearly stated that it?s SP1 RC Refresh 2. Whether you want to believe it?s the RTM version of Vista SP1, this version has been assumed by many Vista enthusiasts as final RTM copy of Vista SP1, and been used to slipstream to Vista RTM to create integrated Windows Vista Service Pack 1 ISO DVD image with fake ?self assigned? version number such as 6001.18000.080126-2040 and 6001.18000.080131-1830.\"
So enjoy the release candidate 2 build. It is a good one, just don't think you have the latest RTM version.