VirtualBox or a PC?

[Machead]

Sorry posted in the Mac section, but no replies so I'm hoping a bit more joy here!

So I'm a web developer that needs to test websites in a whole load of PC browsers - I'm running Mac OS 10.6.6. I don't know whether to use VirtualBox and XP/Vista or actually get a cheap PC netbook.

I'm currently running VirtualBox 4.0.2 with a spare copy of Windows 2000 (yes I know, its what I had lying around!). I have the latest version of Firefox installed on Win 2000, but I find there are significant differences (CSS mainly) between how a web page displays in Firefox under VirtualBox vs an identical version of Firefox on a standard PC (say running Win XP/Vista etc).

Is this due to me using Windows 2000, or is this as good as it gets and down to limitations with VirtualBox. If use VirtualBox and purchase XP/Vista and install all the PC browsers onto there, can I expect to get identical viewing and behaviour results (HTML, CSS, Flash, Javascript etc) as per viewing them on a separate PC.

I'm not doing any particularly fancy websites - I just want consistency and reliability when checking them in all the browsers.

What does anyone think? Thanks in advance.

[Sasquatch]

Please no cross-posting. I've replied in your other thread. Locking this one.