Best method of doing continuous data protection for Small Business Server 2003

I am researching different ways to implement continuous data protection at my company.  I am using Small Business Server 2003 and would like to be able to provide continuous backup to general data, exchange, sharepoint and sql.  There seem to be so many ways to do this.  Should I use a third party software such as Veritas Backup Exec 10d?  If so, should I send the data to a NAS, external hard drive or some other data storage option?  Should I use a solution such as Sonicwall's 2440i?  A couple of things to consider:  
1.  I am currently backing up about 60 GB of data but I anticipate that this could double in one year.  I am currently using BackupAssist for this.  
2.  I am doing nightly backups to a rotation of  external hard drives that are taken off premises daily, I will continue to do this even when I do CDP.  
3.  I am currently running just one server but this could increase to 2 servers in the next year.
4.  A nice added benefit that I have considered with a NAS is additional storage space that could be utilized by users for archived data that is used infrequently.
5.  My maximum budget for this would be $5000 but I would like to accomplish this for less than $3000.

Thanks in advance for you advice!