Monkeybob/any other interested parties:
Consider some of the needs of typical audio software:
- relatively close coupling of the audio hardware and the software, to the extent that the audio hardware driver is often addressed at the application level. ie, within the application (cubase in this case) you define the audio driver - like ASIO, or WDM, specific to your card. This is to allow the software access to the relatively specialised capabilites of soundcards used on digital audio hardware platforms.
Then consider the characteristics of emulation:
- the emulated environment is abstracted from the physical environment, so that radically different environments can be simulated. This is almost always done by providing a lowest-common-denominator software emulation of a capability or function. Specific hardware features (like direct monitoring) are usually sacrificed to do this.
So, while keeping in mind that sound is a function of time:
Close coupling = fast, low latency, and topologically fragile. Usually necessary for digital audio work.
And Emulation = slower, more generally compatible (which is why you often see stuff like "soundblaster compatible" described, in the example of game system requirements, or in bioses). I'm not referring to emulation within GNU/linux here, I mean emulation on any platform.
Nutshell conclusion:
You're really pushing a ton of shit uphill with a tongue depressor if you want to get an audio app like Cubase running under VMWare/Wine on a linux box. Companies like Digidesign (for example) are total wankers in this regard, because their modus operandi is to create/cripple functionality so that it cannot be emulated, meaning you need to periodically need to BUY A NEW PRODUCT from them. They don't give a shit about the art you create surviving for long periods of time, they want your consumer dollar.
To give you a good practice scenario to follow should you want to, if you're going to do audio work on a linux box...
1 - use JACK. This means the audio app you use doesn't need to know a damn thing about your soundcard, ie the hardware is not being addressed at the application level. This allows you to avoid Digidesign leprosy, like the interdependent relationship artificially maintained between pro tools and the digi001. I'm using this description in a totally general sense to illustrate the fact; Cubase is only slightly less cursed than Protools in this regard.
The logical signal chain would look like:
soundcard X --> JACK ---> application X
JACK manages to keep the latency extremely low, whilst providing abstraction between app and hardware, by presenting the raw capabilities of the soundcard as a service. The app only sees the abstract service.
It's not perfect, it's just a step in the right direction in terms of topology. JACK can run on most unixes, like BSD and OSX, not just Linux.
2 - take a hard pill on the app front. Think of it in terms of which functions you need, not which program you need. You will not cease to be a creative individual if you do not use Cubase (no intentional double negative there

. Map out the functions in Cubase you deem important, and work out how to do those same things in another program or combination of programs. I don't mean this in any disparaging sense, but you probably don't use 100% of Cubase's features. Therefore, you can almost certainly work your way around any feature scenario using native GNU/linux audio apps like Ardour or Rosegarden. Think of the functions you're trying to replicate in terms of their end effect of the soundwave, not in terms of "this isn't like cubase, therefore it sucks".
If you see yourself as being dependent on a particular program to make music, then you are in trouble. If you really are dependent on a particular program to participate in the musical world, then you will probably not be participating in the musical world for very long. Audio applications aren't like instruments, they don't stick around in the same form for more than a few years. Be prepared to shift, don't wait until you have to shift, because by then you're risking your music.
3 - Just to temper things, don't blindly take the plunge. Do your research, make sure you use well-supported hardware, and ask questions whenever you need to. UbuntuStudio is a good place to start, it's easy to install for a new user, and a lot of the tweaking/hacking that used to have to occur before you could start audio work is done for you. Planet CCRMA is also pretty capable, but you might need to get your hands a little dirtier. Be persistent, and don't be put off by people like me who'll occasionally come out with statements like "Fuck cubase with a big rubber cock". We mean well, really.