Need help with my Mac and a VGA video switch

I currently use my Macbook Pro at my desk with a Samsung LCD that I've had for quite some time to have a dual monitor desktop and it works great. I also have a nice Windows box that I was just going to turn strictly into a gaming machine so I don't have to drop $2000+ on a Mac Pro, but I want to use my LCD monitor for that computer as well. I found out today after plugging in a VGA "Y" adapter cable that I need to actually get a 2-port VGA switch. No problem. But the part that I don't seem to understand is that the information I'm seeing says that if you plan to run a PC/Mac combo on one monitor you may have to have some sort of adapter for the Mac end of things? Doesn't the Mac use a standard signal? I do use the DVI-->VGA adapter that came with my MBP if that's what they mean. Can anybody give me some advice on this? I just don't want to blow money on a switch and then find out that I didn't get the right stuff.