The short answer is: No.
The longer answer is: Not yet...
VBox's 3D support barely counts. It does provide 3D support but absolutely no performance. VMWare seems to perform a lot better (note the benchmark is on a Mac) and that might be playable. The downside here is a large pile of cash (I'm not sure what 3D support is like in their free offerings).
But if you want to take full advantage of your hardware for Windows-only games, there's only one solution and that's to boot into Windows. I'm afraid to say that's likely always going to be the case for that subset of games.
The only other near-acceptable solutions available:
- Fight Wine (when it does work, it tends to work really well)
- Buy a console.
- Lobby the developer for a port.
There are all sorts of server technologies that may filter through in time:
Nvidia+Vmware are working on a multi-head virtualised gaming platform but I honestly don't expect this level of integration to be in consumers' hands for another decade, if not longer. Graphics manufacturers want us to buy dozens and dozens of cards and virtualising hurts that aim.
You could reverse it and have a Windows Server host VM and paravirt a Ubuntu desktop, with shared 3D but again, I'm not sure what the performance would be like. And it's a ton of cash to do legally. The desktop-host isn't as good at all.
Xen won't paravirt a Windows install, so there's no point looking there yet. It does have PCI and VGA passthrough modules but they're locked to one VM so you'd have to have a graphics card for each install. Urgh.
Note I'm really only talking about 3D graphics here because the rest are solved or nearly-solved problems. CPU virtualisation is mature with paravirtualisation and CPU extensions like Intel VT-x and AMD-V. Peripheral passthrough is fairly low bandwidth so is simple to share.
Graphics are lagging because sharing them in the way we're talking about is not a commercial necessity for manufacturers. It does seems to be going that way though (for high-end render farms and server-based workstation consolidation) so watch that space.