frame-set's or one frame via SSI/templates ?

What is most popular use out there on the big wide internet, when using web applications (and dynamic content). To use html frames or to only have one frame (that is assembled via. SSI/templates). I see plus and minus for both. frames are complicated, and it's hard to tell which frame to

errorPage in a multi-frame enviroment.

How would I make sure my errorPage get's displayed in a specific frame in a frame-set ? - Jakob