Dell 1920 x 1200 as focus aid

Hi,
In interior shots would it be a good idea to use the Dell to assist with focus?
I'm not talking about colors here, just focus. In theory this Dell has more lines than what the Canon Xh-A1 can output, so any reason why I can't use my computer monitor to monitor focus on the Canon?

Can you give me any idea to assist focus for exterior shots where I don't have access to power sources?

Now for color, can I hook up a standard Pro CRT Sony monitor?
Thanks
Phil