Should I Get Snow Leopard or Lion for old MacBook Pro

[PetC]

I have an 'original' 17" MacBook Pro (almost 5 years old now) and although it is running kind of slow with max. ram (3 GB) I am wondering if it is/will be worthwhile waiting for Lion, or load Snow Leopard now, or just stay with my current Leopard OS? In other words, does the idea of staying with this older computer and just getting a new OS make sense? Will Lion even run this MacBook Pro?

 

[Nermal]

If it's from the first "batch" then it'll be 32-bit and won't run 10.7.