Well, I can also elaborate a bit about that. Actually the problem is a bit more complex - a virtual CPU works _exactly_ like a normal one, so if a normal one may perfrom a MSAA/FXAA pass, than a virtual can do this as well, no problem. That's the whole point. So if we are talking about software emulation rendering here - we are scored. Antialiasing in an emulator (a "hard mode" emulator, such as VirtualBox, VMWare and such) should work out of box! Except that no antialiasing works in software emulation (no hardware acceleration).
Sooo, we are moving to the root problem - hardware acceleration. How do one emulate a hardware acceleration? That's right - by not emulating it! The only way to hardware accelerate an emulated program is to pass all the GPU commands and data back to the host OS (the one which is running an emulation software, such as VirtualBox, etc) and perform it on the host OS, using host drivers on a host real GPU. And it works fine, except for the DirectX games, because no-one knows exactly what DirectX actually does under the hood. So all DirectX games are running through some soft of API/driver emulation in the guest system which tries to behave like DirectX, but usually fail miserably (for instance - VirtualBox hardware emulation actually translates all DirectX calls into OpenGL using code from the Wine project), due to numerous undefined behaviours, uses of undocumented or poorly documented DirectX features, driver gotchas and stuff like that. And driver-mode MSAA/FXAA (and we are talking about OLD games here, way before sharers era) is just a black magic that generally does not work even natively, so most emulators just ignore it, because it's such pain in the ass.
That said, it might be possible to enforce antialiasing for a game within a guest system by the same means as you enforce antialiasing for a game within the host system, via drivers. As for the host driver it's the same thing as a native application (it doesn't really care what's coming in and how it's get there) it will enforce antialiasing for it anyway. MXAA is a fat chance - it's a bit too complex to enforce, but a fullscreen one is just fine - it's just rendering in n times bigger resolution and then scaling the image down. But you may want to rename exe files for an emulator software into something else. Or somehow tell your drivers not to use any stupid hacks and quirks it might be using for a given application (usually detected by exe name), such as disabling antialiasing.
I do generally prefer playing old games in Linux under WINE. I do find it much easier and more convenient than running VirtualBox with Windows XP within Windows whatever else. I also think that it should be possible to enlarge a Wine window to match your resolution with whatever filter you want (it sounds like a more convenient "Screen Zoom" application). Never tried it though. But if you are interested in running Wine I may try to find or patch it.
And, BTW, if we are talking about a windows "fullscreen mode" - it actually changes your resolution to a lower one. Which means that filtering stuff is not a videocard's job anymore, but your monitor's one. You should check your monitor's menu/drivers for a filtering config. Mine doesn't have such a feature, but I know some monitors have it.
