I have a MacBook Pro, fairly new, intel based, 4G RAM. I may need to work on a Sharpoint project, so I'm assuming I'll need Visual Studio and Sharpoint Designer. Is using VMware an option, if so, what Microsoft OS should i use, and what general VMware settings should I use (RAM and disk size).
VMware Fusion is a good option.
As to Microsoft OSes for SharePoint development, you have two choices: Windows Server 2003/2008 or Windows 7.
I've been developing with a Windows Server 2003 VM for SharePoint for about a year. I'm still using Server 2003 because it matches our dev/qa/prod environments.
I would agree with the post above that VMWare is a good choice. As for what OS if your are doing true enterprise level SharePoint development then you will need 2003/2008 however you can run WSS on vista. As for using SharePoint designer I would avoid it for SharePoint 2007 development and instead focus on getting a solid solution structure defined and use some tools like WSPBuilder and your be off to a good start. If your doing SharePoint 2010 SharePoint designer has got a lot better and the new support in Visual Studio 2010 for SharePoint is great.