If you want to buy n900, you must keep your 5800! Same battery, ideal fast-charger! And if **** happens, a full charged battery could be your best friend (and believe me, "it refuses to boot, I must reflash but USB doesn't charge my n900" is a PAINFULL situation and not so hard to reach). Excuse my English... I'm Spanish. P.D. We still love you, Paul Octopus... :'-(