Tech, thanks but so far no indication of any problems with 256 megs.
Only one oddball behavior I've noted, and while that could be just a coincidence of timing (started right after installing Comodo) I don't believe in such things, at least not on computers.
Now when I download JPGs, especially relatively large ones, they progressively display fairly large "chunks" at a time, as much as 1/4 or even 1/2 of the image, with long waits in between additional portions. I've been accustomed over the years to JPGs loading and displaying a few additional lines at a time.
But total download time for the image seems to be about the same as always, so it's a curiosity thing rather than a speed problem. Over at Comodo, they suggested a problem with Firefox setup, but I haven't touched that in ages and it's been a while since the last update (to 2.0.0.2). The timing certainly seems to point at Comodo.
My ISP (unfamiliar with Comodo) suggested that one possibility is that Comodo "sits on" a large number of packets while checking and releases many to the system at once. Over at the Comodo forums, they don't even seem to understand what I mean when I raised that suggestion.