I had a homebrew PSP ~2006 or so, got stolen. Wah.

Recently picked up another one and ...my god, things have changed.

So I've got it running 1.5 and now I root around the web and I see soooo many acronyms and firmwares but I've got no clue as to what they are, what they do and more importantly, why I'd want to ditch 1.50 to get 'em.

I looked, I swear it, can't find a simple explanation? I feel seriously old. Halp?

Thanks much in advance.