We can still buy the foam boards and cut them to fit behind the studs and then tape them

Sounds OK.

In many cases, though, you can cut the screws on the base and top plates with a reciprocating saw and remove the stud wall in toto and replace the same way. Or you can use ccspf if it's in your budget.

You should consider having spray foam insulation done. It is a little more costly but you get a much better job and it fills in all the voids. It's normally done after all the electricial wiring work is completed.

I've done what you talked about, cutting 2" foam board and inserting between the studs but it is very time comsuming and it will never work as well as the sprayed in foam.

i have to agree with rexg...it's ok your studs are up...don't know if they're still showing it, but on diynetwork.com, they show exactly what it looks likes to have the foam installed...one of the hosts had it done on her basement make-over.

what you might want to do before installing insulation, is use a moisture barier paint on the concrete, then the insulation..that's what my ds1 did (we're in se mi) and their home is about 60 yo...

I third the motion for spray foam insulation. The closed cell (at R 6.8 per inch) is my preference--it will also seal out air infiltration (rigid insulation won't) and provide rigidity.

You are trying to fill in the simplest way possible the space between the back of the studs and the foundation wall.

If that space is a half inch or less, you can use a handheld polyurethane spray such as Great Stuff. At anything greater, it's usually easier to cut strips of XPS foam board and slip it in as you thought about doing in your original post.