We're running windows server 2003 and as of now, we are using NTBACKUP - however, we are looking for another tool, preferably something free which offers mediocore features.
The reason we want to move away from NTBACKUP is that it is not very reliable. Sometimes our full backups are 70GB and sometimes they come up to 110+GB with the exact same options and files selected. Incrementals (run a day after) also run up to something silly like 40GB which is impossible since nothing much changes on the server.
edit: We're looking into remote backup too (something like jungle disk) but for now, we have 2 hdd's; one for offsite storage and one onsite.
edit1: Okay so one thing I'm trying tomorrow is a tool called 'handy backup'. Apparently we already have a licence for it on the server so I'll see how that goes. Still open to suggestions - we did have a trial of 'shadow copy' however, the licence (500$) was a bit too expensive for our liking.
NTBackup isn't very flashy, but it does work fine. Certainly, if you want more / better features then moving to a more feature-rich backup management program may be in the cards.
It sounds like you haven't done a lot of investigation about the problems you've been seeing. I'd strongly suggest that you pinpoint the root cause of these wild size discrepancies, as you're likely to have the same problems with whatever backup program you end up choosing. You could have in-use files as a result of server-side applications locking files, etc.
If your "backup" is just a couple of hard disk drives I'd argue that you probably aren't taking backup seriously enough. You ought to be thinking about what the cost to the business would be when you lose weeks, months, or all of the data, and spending accordingly.
For online backups (which I highly recommend) I have used USDataTrust in the past. Very nice set and forget. There may be more cost effective solutions but 2 years ago they were great. Just Google "Online Server Backups".
HTH Mike