Adding a new hard drive, and using geom

[Joshua Isom]

I bought a second hard drive for my computer since my /usr partition 
was getting full.  I don't want to deal with hardware raid since I 
don't want to be dependent on a certain hardware vendor or chipset, so 
I'm wanting to go with geom.  I'd prefer to not have to backup all my 
data(I know I should anyway, but it's a 500gb hard drive, and drives 
are growing faster than backup solutions).  Would it be possible to do 
a geom stripe to expand /usr and keep all the data or would I just need 
to backup everything, and then put it all back?  If I must deal with 
backing up and erasing, and considering that the current /usr and the 
new drive aren't the same size, how would I go about mirroring other 
paritions and striping /usr?  Would that still be easily bootable(no 
special hacks or workarounds)?

Any tips or other recommendations would be appreciated.