Spot on Skuzzy...
Umm sorry but Skuzzy just verified my point.
It is not the size of the drive, per se. It is the areal density that controls the absolute performance rates of drives. As it turns out, most higher capacity drives have higher areal densities.
Please note I never stated anything otherwise. The rising trend of size/performance is indeed through advances in densities and larger caches among other technological advancements in the new drives.
A drive with similar characteristics and larger data volume (meaning usually higher density) gives out more performance. As what goes for that article at Tom's they compared the new large drive to an older generation smaller disk. An example very similar to the situation of the OP and they stated it clearly.
Can't believe it's still even under debate. I'm quite amused by gyrene's condescending story about higher rpm drives etc. when in fact they have nothing to do in my example of getting a great price/performance and great volume/price ratio addition to the system.
As what goes for your worry about aging sata 1 spec ports on his motherboard I suggest reading the wikipedia article:
http://en.wikipedia.org/wiki/Serial_ATAAs of April 2009 mechanical hard disk drives can transfer data at up to 131 MB/s,[8] which is within the capabilities of the older PATA/133 specification. However, high-performance flash drives can transfer data at up to 201 MB/s.[9] SATA 1.5 Gbit/s does not provide sufficient throughput for these drives.
The new Tb drives are almost all about benefits with a little penalty in seek times and once volume per dollar ratio is taken into account there's just no question what the choice should be for anyone but the most hardcore enthusiasts.
My point stands: A full reinstall is an excellent opportunity to get a new large low dollar/gigabyte drive that blows away the existing drive in performance.