Until recently, Vegas Movie Studio lacked the capability of authoring menued high-definition discs at all; the menus were compatible only with standard-definition DVD (Blu-ray/AVCHD DVD authoring with version 9 was possible only from the Vegas timeline, which did not support menus). That was the limitation of DVD Architect Studio 4.5, which came with the previous release of Vegas Movie Studio (version 9). But with the very recent release of Vegas Movie Studio HD 10 Platinum and Platinum Production Suite (both of which come with the new DVD Architect Studio 5), the consumer Vegas programs can now author menued HD Blu-ray and AVCHD DVD discs in addition to menued SD DVDs.
As for the cheapest version of Vegas, Vegas Movie Studio HD (standard), it can work with HD content but lacks any HD or SD disc authoring capability whatsoever. In addition, the number of supported export formats are more limited than its pricier Platinum versions.
And since we were talking about the ~$100 consumer video editing packages, all of them are currently strictly 32-bit. Hence, they cannot use more than about 2GB of installed system RAM even if your system has far more than that and is running a 64-bit operating system.