Probably only Firefox. Chrome is, in my view, a doubtful prospect, Being related to Google is no privilege and from experience, their extentions are not always secure.
What I would say is, don't be pressed into upgrading to Lion / Mountain Lion for some extra browser benefits. Snow Leopard is an excellent OS X, far better than Lion and despite not being supported is still a totally reliable program.
Is your memory level high enough? Safari is something of a hogg with memory.