That's an issue that plagues all hard disks. You buy a 250GB drive, you only really get about 232GB of useable space. This is because technically, it's a 232GB drive. The one you're talking about is technically a 27.8GB drive.
But hey, it's bad marketing to sell it as 27.8 so why don't we round up to a nice misleading number like 30. That's seriously how it works.
The reason for the space discrepancy is that on marketing four-color glossies, they are citing drive space in terms of "decimal" billion (1 gig = 1,000,000,000 bytes) where as the computer will report the drive capacity in terms of "binary" billion (1 gig = 1,073,741,824 bytes). Thus for a 30 gig iPod, you have:
30 x 1,000,000,000 bytes = 30,000,000,000 bytes
30,000,000,000 / 1,073,741,824 = (appox) 27.94 gigs. However, there is indeed a small amount of the space in an iPod used for the firmware and other supporting files (such as files used by iTunes to help manage the library and such). Of course, I would not be surprised if the same thing is true on the Creative Vision:M as well.
Of course, the same thing is true with harddrives in general. Take the 250 gig example:
250 x 1,000,000,000 bytes = 250,000,000,000 bytes
250,000,000,000 / 1,073,741,824 = (approx)232.83 gigs.
As to the original question as to which MP3 player to get to replace an aging iPod. Well, the first and obvious is to just fix the iPod by replacing the battery. It would be the cheapest option, and as others have said, it is not difficult to do.
If you are really dead set on replacing the iPod with something newer with a bigger capacity, the next option would be simply to get a new iPod (if you are going to - might as well bite the bullet and go all the way and get the 80-gig model). If you really like the iPod and don't mind iTunes, ignore the "iPod bashers". They are entitled to their opinion and I actually agree with some of their points, but in the end, who really gives a fuck? If you are happy with what you got, continue to use it!
Of course, getting the Creative Vision:M would be an excellent choice. In fact, I wanted to get one myself when I was looking for a harddrive-based MP3 player, but nobody in this area had them! So I ended up "settling" for a 30-gig iPod (now wishing I did get the 60-gig that was available at the time, as I have my 30-gig completely full, so whenever I want to add new stuff, I have to remove some of the stuff I already have on there). I do have a "solid-state" MP3 playing in the form of the
Creative MuVo Slim, but it is a few years old and only hold 512 megs. But hey, it works perfectly for it's intended purpose in that I needed something small and durable that I can use while working out at the gym, plus it really does have a good sound quality. And admittedly, I'd much prefer being able to just drag and drop my music into the player as it appears as another drive on my system. No special software needed to manage the device (although I can use it if I wish - hell even my trusty ol' copy of Winamp does it, as well as manage my iPod - yes, if you don't like iTunes, there are third-party programs out there, including one that will "force" the iPod to act like a regular drive to simply drag-n-drop music to (
Anapod is an excellent choice, but alas, I do think it is bullshit to have to pay another $25 or so bucks to get something that should be native to the device in the first place).
Despite what some folks say, the iPod is definitely a valid and solid option. Most likely if my iPod craps out, I'll probably most likely just get another one, especially since my car has a dedicated "iPod interface", so it is friggan awesome that I can listen to it in my car without needing one of those crappy little "FM adapters". But, if you don't want to stick with iPod, then I would also recommend the
Creative Labs Zen Vision:M.