There are many good reasons to do the opposite, especially if you plan on
doing 95% on Linux.

First, there is security. Linux is the best. It has few viruses, malware and
trojans and most of those are of little threat due to built in security such as
no central registry, modular structure, hierarchical file structure, isolated
root and user areas and password protection for any changes to the system. It
makes sense to run the stronger OS as your host and the weaker one as the guest,
in the VM.

Second, Linux drives do not slow down over time as there is no fragmentation. If
you run a VM in Windows it will slow down as Windows becomes fragmented. If you
run a Windows VM in a Linux host then only the VM will need to be defragmented,
instead of your whole drive, a much faster process.

Third, Linux never needs to be rebooted after an update. You will have to stop
your Linux VM in order to re-boot Windows as it goes through its update process.
If you run a Windows VM in Linux then you only need to re-boot the VM and you
can keep working while that happens.

Fourth, Ext4 is here. It is available in the next Ubuntu release (9.04) and will
be the standard before the year is out. It is much faster than anything Linux
has had before and M$'s file systems are not even close to the current standard.
Ext4 can handle individual file sizes up to16 TBs. It can handle volumes up to 1
exabyte (1 quintillion bytes) or 1 million TBs or 1 billion GBs. File transfer
is smoking fast as it can handle much more data at one time. Not only is it
fully journalled, but it is provides on the fly checksums. It shatters current
standards such as the 32000 subdirecory limit for ext3 in a single folder and it
allows all chararcters except null and / in file names which can be up to 256
characters long. In short, it will revolutionise the way we handle data. There
are even better ones in the works such as btrfs which extends file size to16
EBs!

Fifth, Linux seldom crashes and they are usually isolated to the application or
the session. Lockups will happen but they are rare. Usually you don't have to
re-boot but just press Ctrl-Alt-backspace and login again.

Sixth, choice. Running VirtualBox in seamless mode you can have a GNOME panel at
the top and a Windows panel at the bottom and share the same desktop and you
still have unlimited virtual desktops. You have a choice of desktop environments
and can pretty much do whatever you want.

There are more, but you get the idea.

There is one good reason to do it the other way around. Linux requires a smaller
VM and will run more efficiently in a VM than Vista which is a resource hog to
begin with.

On a more neutral note, VMs can be tailored so that you can set the size and
allocate whatever resources to the VM that you want, which ever way you choose
to run it in the end.

The choice is yours and only you can decide what works for you as you have to
live with the results. Either way you go, we can help you set up the Ubuntu
client in Vista or set up the Vista client in Ubuntu.