My N900 battery lasts for around 30-40 hours depending on the usage. But I've noticed that its Internet Surfing using GPRS that consumes the battery. If I serve internet using GPRS , a fully charge bettery's one bar will go down within half an hour or sometimes even less.

Sometime back I've read that old sim cards drain your bettery fast. Mine is a 7 yr old sim card. So is it the sim card thats putting strain on CPU for catching the signals?

Do modern sim cards have a better chip so that catching signals don't put too much strain on the CPU? Do I have to change the sim card?