The JPG should give you the resolution - for example, the first one you posted is 501x600. There are many ways to get that info, the easiest might be to just right-click it and go into Properties.
I have to tell this story - I was trying to decide where to get a couple rolls of film developed today and decided to try one of the "true" photo places rather than the usual one-hour minishop in a larger store. That way, I could also ask about drum scanning, cost, resolution, etc.
First place I called was somewhere that bills themself as the best color lab in town. I asked how much to have a negative scanned - the woman said $5. I knew I was out already but just for reference, I asked the DPI. She said 300.
300! We're talking here about scanning them ourselves at 3200dpi, and the top place says they scan at 300dpi? I said that can't be right, are you sure, you won't get much out of a negative at 300dpi. She said (rather snippily) "best quality in town, you can come down at look" and after I inquired again, she said, "look, I don't have time to argue about this, the guy that does it isn't here today." OK, fine, cross THEM off the list!
I decide to drop off my film at another place that I haven't tried before, but is at least more consumer-oriented rather than primarily doing business work. I asked them, they say there are three different quality levels, the top was $2/picture. I think the cheapest was 50c. I asked about DPI - again, was told 300dpi. The first guy I talked to didn't want to discuss it but a woman nearby joined in and fortunately had a better idea. Apparently the print shots measure it by the print you'll get from it - ie, all the different scan qualities are 300dpi, but the top one is 300dpi at 8x12, or something like that. She wasn't sure what the actual resolution was but said that the medium ones usually ended up as around 9 meg JPGs and the top was maybe 25 megs, and took probably 20 minutes or so for each scan. She also threw out a digital ICE reference, so at least she knew something, unlike the other people that I talked to!
Moral of the story is... photo labs speak a different language than computer people, and while I have no doubt that the quality of a drum scan is unbeatable, it would take only three rolls of 36-exposure film before you're spent more than it would cost to pick up the Epson 4490.
