The problem with proxying is that every application you use has to specifically support proxy. Flash player, for example, doesn't seem to have SOCKS support.
I've developed software (tun2socks) that allows you to forward all TCP and optionally UDP through a SOCKS5 proxy, system-wide, without requiring any application support (which Flash is missing). To put it very simply, my software simulates a network interface and a virtual router behind that interface which forwards all connections through a SOCKS proxy, and by using it as the default gateway you get proxying for everything. The following guide explains using tun2socks with SSH forwarding (exactly what you want).
It it a little clumsy to set up however. If you want to automate it, you're on your own.
If you follow the guide successfully, all your programs will go through the proxy automatically, and you should disable proxy in the browser itself.