i386 or x86_64 tree?

[Robert Moskowitz]

How do I tell which update tree for Fedora 14 a system uses?

I have maintained a repo tree for i386 locally for some time.   I have 
always had 'older' equipment.

Well I just picked up an HP dc5000 and I noticed after the install, that 
the upload profile stated it was an 686 platform (Intel P4 3.2Ghz).  I 
see i686 rpms on the system and there are i686 rpms in both the i386 and 
x86_64 update trees.  So I need to know if I now need to pull down the 
x86_64 tree and point this new box to it instead of the i386 updates....

I believe this would be the $basearch value I see in the yum .repo files...