backup options

[gambitt]

I've only ever backed up my important files but now it's time I backup everything. Currently I have:

1x 74GB Raptor (boot drive)
2x 500GB Wester Digital 7200's

I don't fancy backing up 1074GB of data to DVDs! I use Ghost all the time in work for creating build discs and I like the fact that it compresses the data.

I also want to make regular backups so RAID would be the ideal setup, but in order to backup 2x 500GB drives I would need another 2x 500's to mirror them, right? Well I don't have space for another 2x500's

I suppose I could use an external drive but say I get a 400gb USB drive, what software will compress 1074GB into 400GB?

 

[gambitt]

I haven't got a RAID setup, just 2x 500's side by side with lots of video data *cough* episodes and films

I guess I could backup the episodes onto DVD neatly and cut my data down. Then maybe I can get 1x500gb drive to mirror to and just keep stuff on the 2nd 500gig drive that I already have on DVD.

What's a good piece of backup software that just backs up changes rather than backing up everything?