SPF entry in DNS to counter Spammers

Each day I get a few "bounces" of email messages I never sent. To counter this I am asking my ISP to insert an SPF record in the DNS entry for my domain name. The problem is that spammers can forge an e-mail message from me by putting my e-mail address as the sender's address. To counter this a list of the mail servers I use can be inserted in the DNS record for my web site. When a mail system gets a message claiming to be from me, it can check if it came from one of the list of mail servers I nominated. I not sure how well this works in pratice. There is the catch that if I have to cange where I send my mail from, I have to remember to change the DNS record, or my mail will be treated as Spam.