I was thinking of buying the samsung 226bw to use as a second monitor and with my 360 i want to connect the computer using dvi and the 360 using vga, my question is that can i keep them both connected to the monitor and switch between inputs or do i have to connect either the xbox or the computer whenever i want to them.

Sorry if this sounds a bit confusing

If your monitor has both inputs, yes you can hook up your 360 to the VGA port & have your computer on the DVI. The monitor's menu or the OSD keys should allow to switch from one input to the other easilly.

If you're lucky it could also have picture-in-picture allowing you to display one input in a corner on-top of the primary input being used but not all monitors have this option.