which keyword should i choose?

i have an interesting doubt.
i have a site which is focused on X.but what my traffic is interested is in Y.to get listed in google i must optimize the site around X.
but to get clicks and good CPC i must target ads around Y.

so am confused whether to make my site around X or Y.
or is there any other solution available which can help me get a PR with X and get clicks with Y? like writing the content focusing both X and Y.
i can explain more if what i have written is not clear enough.
thanx guys for the time

 

make a part of your website for X to get the traffic and add some Y info to get the clicks

 

create a page www.yoursite.com/Y and write about Y and leave the site to be focused on X. That's what I'm doing and it payed out a lot, most of my visitors come from google to www.yoursite.com/Y page