Why are you bothering to upgrade to Lion?
If your machine is one of those that can't upgrade to the better Mountian Lion, then it's much better off remaining on Snow Leopard because of all the legacy software your running won't need to be replaced.
The Lions and beyond won't run your PPC software, and likely most of your Intel software neither, no Rosetta!
A older machine that can only run Lion is a dated machine, and likely due to expire soon.
I can't see even bothering to go to Lion and having to buy all new software for a old machine, not at your stage.
A newer 10.8 machine would be a better choice, because you know Apple releases a new OS X version every year now and the year is almost up, so if you get to 10.7, then your going to be behind again shorty anyway on the old machine, but the new machine you can upgrade OS X to the latest new version.
It doesn't make much sense at this point and time to upgrade to Lion for you, the older machine will run best with Snow Leopard anyway.
If you MUST use one of the OS X Lions, then I suggest a new machine, that way it can be upgraded further.
Apple is still issuing security updates for Snow Leopard, it's got a 1/3 apx market share.
OS X 10.4/10.5 need to upgrade, 10.6.8 ok still
