Just to dot the i's and cross the t's...
I copied the old fs to the new lvm partition last night to ensure that the different fs (/va and / were all in sync. Interestingly, I had to remake initrd again, but that is (now!0 a trivial task! All the applications work correctly, so I'll give it a few days to see if any oddities arise, then I'll reclaim the old static partitions and add them to the volume group.
As a general observation, I am impressed at the 2.6 kernel's memory management. My system has about 970GiB of free RAM, with a 2GiB swap file. With the 2.4 Kernel, RAM use was usually up at about 900MiB and swap file useage generally crept up to about 1.5GiB - particularly running Opera which seems to be a memory hog!
With the 2.6 Kernel, RAM useage tends to hover at about 400-600MiB, and swap file useage rarely gets above 400MiB, so the memory management routines seem far more efficient. The only thing I have noticed is that Opera freezes for a couple of seconds periodically - so perhaps the Kernel is working harder to memory manage this particular memory hog!