Sun V60x, V65x

I am not exactly a newbie, but I don't really know about RH Enterprise
Server.
Like for example, what is the difference between it and the RH
distributions I 
have downloaded and installed via kickstart? (Which include 6.2, and 7.0
- 7.3)

According to Sun, their new machines are certified to run Red Hat
Enterprise Server.
Does that mean I can install and run RedHat 7.3 (using the SMP kernel)
on them as well?

Also, since we run ECAD applications which can utilize 8GB and more of
main memory,
I assume we will need to run the Enterprise kernel rather than the SMP
kernel.
Does anyone have experience with running the Enterprise kernel?  If so,
is there
a measurable performance hit from running it verses the SMP kernel? Or
are there
any stability problems or application compatibility problems that come
with the
upgrade?

- Mark