SHA1 usage for passwords, alternatives and advantages?
If your password database will never be compromised, you can store plaintext passwords and nobody will be bothered. The only thing about plaintext passwords is that they can be accidentally remembered by admins who see them - a simple base64 will fix that. Equivalently, MD5 or SHA1, with salt or without, is just as fine.

If your password database is possibly compromised at some point in the future, a single SHA-1 with salt still means that 99% of the user passwords are crackable on a laptop - basically no protection at all, except inconvenience. So if this is the attack you are worried about, you need to switch to something which has a sequential iteration count that isn't trivially small. PBKDF2, bcrypt and scrypt are all good choices for this.

(Note: assuming your password database will never be compromised is a really bad idea, if it wasn't already obvious from the answer.)