I'm running a 667 Mhz DVI TiBook with a Gig of Ram - right now I'm using 10.3.9 - I'm wondering if people think it would be worth my while to go up to 10.4.9, since I've got disks for both. What's the speed difference? In general, I've found that OSX works on something of a curve and, for most of the older hardware I've been setting up for people (a Pismo, a few Lombards, some G3 iBooks) that Panther is the fastest system. Indeed, in most cases, Panther seems faster than Jaguar. So, in this case, would a 667 TiBook be fast enough that, perhaps, it might take advantage of the general enhancements of Tiger? I've only used Tiger on high-end Intel platforms before, so... Also, not that I want to put too much into this - but, right now, I'm using the stock drive which came with the system (I presume a 4200 RPM 30 Gig) - would pulling a 7200 one off eBay or somewhere provide a nice speed boost? And, if so, would it cause heat/battery problems?