I've been using VirtualBox for a really, really long time and enjoyed it but now I need to run Unity3D (dev tool, not the ubuntu shell) and this seemingly simple task turned out to be too much for humble graphical abilities of VirtualBox.
The thing is virtual box allows only up to 128mb of video memory (I've tried various tricks described over Internet to make it work with 256mb but with no luck) which is not enough for even IDE of Unity3D to start (it kind of starts but only kind of). Also with direct3d support enabled virtual box crashes when I try to do something in Unity and without it Unity3D IDE looks completely unusable.
I guess I need virtualization solution which capable of utilizing more video resources of my notebook hardware. I have 8 gbs of ram, radeon 5730 video card and also integrated intel card:
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 12) (prog-if 00 [VGA controller])
Subsystem: Micro-Star International Co., Ltd. Device 1037
Flags: bus master, fast devsel, latency 0, IRQ 43
Memory at f0000000 (64-bit, non-prefetchable) [size=4M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
I/O ports at e080 [size=8]
Expansion ROM at <unassigned> [disabled]
Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
Capabilities: [d0] Power Management version 2
Capabilities: [a4] PCI Advanced Features
Kernel driver in use: i915
Kernel modules: i915
I've tried to run unity3d in virtual box using both intel card and radeon with indistinguishable results.
Also, I've got error while installing vmware-player:
2012-08-07T19:08:59.923+04:00| vthread-3| I120: Trying to find a suitable PBM set for kernel 3.2.0-27-generic.
2012-08-07T19:08:59.923+04:00| vthread-3| I120: Validating path /lib/modules/3.2.0-27-generic/build/include for kernel release 3.2.0-27-generic
2012-08-07T19:08:59.927+04:00| vthread-3| I120: Your GCC version: 4.6
2012-08-07T19:08:59.938+04:00| vthread-3| I120: Your GCC version: 4.6
2012-08-07T19:08:59.973+04:00| vthread-3| I120: Header path /lib/modules/3.2.0-27-generic/build/include for kernel release 3.2.0-27-generic is valid.
2012-08-07T19:08:59.973+04:00| vthread-3| I120: Building module vmnet.
2012-08-07T19:08:59.973+04:00| vthread-3| I120: Extracting the sources of the vmnet module.
2012-08-07T19:08:59.986+04:00| vthread-3| I120: Building module with command: /usr/bin/make -j -C /tmp/vmware-root/modules/vmnet-only auto-build SUPPORT_SMP=1 HEADER_DIR=/lib/modules/3.2.0-27-generic/build/include CC=/usr/bin/gcc GREP=/usr/bin/make IS_GCC_3=no VMCCVER=4.6
2012-08-07T19:09:02.872+04:00| vthread-3| I120: Failed to compile module vmnet!
In general, physical cards with 128MB video memory can run Unity 3D just fine, but maybe that setting does more behind-the-scenes in Virtualbox.
I haven't used Virtualbox regularly in a while, but I can definitely recommend VMWare Player (free) for your needs; with the 3D acceleration option enabled for a virtual machine, it runs Unity 3D just fine.
Sorry but no Virtual Machine that I know is able to run something like Unity. You can try to run it in Wine, but don't expect great results. If you want to use it, specially if it's professionally, you best bet is to use Windows or OS/X.
Note that even if it is able to boot Unity, as you create more content it will require better hardware to render it without slowdowns.