general backup questions

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I use XP Home. I did a system data backup and it came out to 24 gigs. I want to copy my backups onto a removable flash drive because someone recommended copying onto a flash drive as being the best method to store backups. I have an 8 gig flash drive. Is there a way to compress the backup file to fit onto my 8 gig flash drive or do I need to purchase another 32 gig flash drive to store onto? Also, isn't it important to copy backups onto dvds occasionally to protect against viruses so the only data lost is after the point of infection? If the data is infected then the backup data copied onto a flash drive will be infected also, correct? So I was thinking of copying the backup data onto a flash drive weekly because it's easier to copy onto a flash drive and onto dvds monthly. Would that be a good method? Thanks for any replies.