"do" or "does"

My friends and I are having an argument over this particular sentence :

"I do want to upgrade my computer though, when does the new pentiums come out?"

The argument is whether or not I could use "do" or "does" in the second part of the setence. For example :

"When does the new Pentiums come out?"
"When do the new Pentiums come out?"

I believe both are correct, they believe only "do" is correct.

Any help appreciated, thank you. I know it is a silly argument, but i'd like to know nonetheless.