hello again...was tired of performing full backups w/ a third party system...& the time that it took...so I decided to use the backup functionality of windows (running XP Pro).here's what I'm doing:1st, I backed up everything w/ a FULL backup (& on the 'Backup' tab, under 'File', I saved that heirarchy as a *.BKS file...so it would always be the same files & folders being backed up)Then...the 2nd time...I chose that *.bks file & performed a DIFFERENTIAL backup. It went really fast & I noticed in the file window that it only seemed to stop on new files I had created...so I assumed everything went well.last night, I performed another differential backup, using the same method; & that seemed to go well also.so...my question is...am I performing backups correctly by using this method...???& if so...how does the backup utility know what files have been backed up from prior backups...???...so as to only backup the files that are new or have been altered...???thanks,SonicMaxXP Pro SP31 person needs an answerI do too

Hi,Your process is all correct, A Differential is cumulative backup of all changes made since the last full or normal backup, i.e., the differences since the last full backup. The advantage to this is the quicker recovery time, requiring only a full backup and the last differential backup to restore the system. The disadvantage is that for each day elapsed since the last full backup, more data needs to be backed up, especially if a significant proportion of the data has been changed.Many Windows 3.1-based backup programs use the archive bit to mark files that have been backed up. Backup does not use the archive bit in any way. The decision as to whether or not a file should be backed up in an incremental backup is based on the filename, its last modified date, and the date of the last incremental backup, all of which are stored in the file set.You can also refer to: http://support.microsoft.com/kb/136621Hope this helps.