Computer deployment question using SCCM

We are using SCCM to deploy Windows 7 to our computers.  If we have an existing computer (windows XP) in the environment  I can put the computer into the deployment collection and image the computer with no issues. 
 
The problems comes up when I try to image a new computer out of the box.  I manually enter the MAC address and give it a computer name in SCCM, but when I try to PXE boot and run the install it gives me an error saying that the computer can find the PXE server (which is the SCCM server).  After about 1 hour I can try to image the computer and everything is fine.  Where can I set the 1 hour sync time to be less?
 
Thanks,
 
Jeff

Are you updating your collection membership after you add the machine in? You could also try enabling Unknown Computer Support. That would save you from having to import the computer in.
 
Justin

If you are on R2, then you can use unknown computer support, which makes it so you don't have to import the computer information.  Just advertise the TS's you want available to the unknown computers collection.
 
The 60 minute timeout is a WDS thing, but you shouldn't be running into that for a NEW computer, unless it's not actually new and it's known to configmgr. 
 
It's possible to reduce the timeout, just search for WDS cache timeout, you'll find a ton of posts on it.