Making portable firefox my default browser. How?

[urlwolf]

This is a silly question, but I cannot find an answer.
I've spent a while trying to make portable firefox my default browser.
Right now it's IE, even though it says in options that it's not, and it says in FF's options that it is.
How the hell did I get into this mess?
I bet there's a registry hack to fix this...

Anyone knows?
PS: this is for my laptop. My desktop, with a parallel config, does the right thing. windows server 2008 both.

[tomos]

one way could be using mousers browser tray switch. You have to add portable browsers to the list
I've had trouble now & again mayself with default browser (some things respecting it, some not) possibly because I usually have a portable version of Opera as default.
I'll be interested to hear what others say . .