Yes, it does seem that way (re JL and RAM), or have machines others don't seem to touch. JL has a Tosh L300-29V which of course isn't the L300-29X that is on Comet site.
JL's Tosh has 3 GB RAM and costs 399.
Comet's has 4 GB RAM and costs 359.
Same video chips and memory, same 250 GB hard drive, same CPU speed etc, same weight. There may be some small difference in battery life (not shown on JL spec).
Looks like the only other difference is the list of software. I'd go for the 4 GB PC, even if they had been the other way round, price-wise, as more RAM often makes a difference, and it's more 'future proof'.
Comet does also mention Windows 7 upgrade option (so it's a promise this one can handle it).
(Just checked Google product search and for those two models, Comet and JL had been charging 499. Laskys were cheaper and it might be that both have been reduced to clear them, because when new Windows 7 is on all the new machines, these won't be "current" and they may have to sell them even cheaper, IYSWIM, to have shelves full of Windows 7 when Microsoft pushes it on TV.)
One difference is that JL offers 2 years warranty, Comet, 1 year (to go to 2 years costs an extra 99 quid).
If it's a Toshiba, I think I'd argue against paying extra - they have had a good reputation since the mid-80s, and if it went wrong within 2 years, might still get repair done for free if you kick up a fuss with Tosh (not that I'd expect anything to go wrong).
Having perhaps left your head pounding "which to go for" I'd print off the page from the JL site, so you have a list of all the software.
You won't care about Microsoft Works on the machine (cut down version of Office) and McAfee isn't that special. Check whether the Tosh at Comet includes all the other (Toshiba) software. I expect it will, since this is practically the same L300-29 as the one at JL.
Assuming the Toshiba software is the same, you just have to weigh up whether you want a lower spec machine (but with an extra year's warranty) for an extra 30 quid.