It very much depends on what type of budget you have and what you are trying to backup (ie. SQL server, Exchange, Linux, etc.). Also tape is very old hat, most backups can be done to removable hardrives, network shares, NAS, etc. which is generally much faster and cheaper than using tape.
Most windows backup solutions rely on Microsoft's Volume Shadow Service (VSS) so there are lost of cheaper options which are just as good as the more expensive ones.
Microsofts Windows Backup in Windows Server 2008 R2 has had quite a few improvements and can now save to UNC and network shares meaning you can just by a cheap NAS unit and backup to that.
I quite like Backup-For-Workgroups with open file add-on uses Microsofts VSS but adds some more functionality such as storing deleted files and keeping previous versions. It can also save to UNC and network shares and can even store backups on remote servers on the Internet.
One company I have had bad experience with is Aconis as tried their SQL Server recovery software recently. Not only was it slow but it was full of bugs and crashed all over the place. there support when was also very slow with it taking a week to get responses which got you no where, so I would avid Acronis like the plague.
If you are looking for a cheap NAS which can hold loads of data we recently bought a
VIA NSR7800 for around £750. Not only does it only use 40watt of power with 8 x green western digital hardrives installed but can hold 16gig of data