I am planning to upgrade the RAM on my 1.83 Macbook.Ran through previous threads on RAM but many different opinions. Should I i) buy a 1G and run at 1.25G or buy 2 pcs 512 ? Any issue with combining different maker. ii)Recomended (proven)brands on compatibility with Mac as warranty and after sales support is almost non existence here in Malaysia. Handling mostly windows application, not a gamer.