Clean Install or upgrade?

[El Burro]

I want to minimize clutter, fragmentation, lost files, system performance, & I think a clean install is the way to go unless this isn't an issue. Anyone?

Also, can I install Mountain Lion on my other laptop for free since my new Macbook Air is eligible for the Mountain Lion upgrade? Can I just "log in" & install it or is it linked to my laptop/serial number.

 

[GGJstudios]

I want to minimize clutter, fragmentation, lost files, system performance, & I think a clean install is the way to go unless this isn't an issue. Anyone?

You may find some useful information in some of the many threads on this topic:

Clean install vs upgrade?
Clean ML install required?
Clean install of ML??

Also, can I install Mountain Lion on my other laptop for free since my new Macbook Air is eligible for the Mountain Lion upgrade? Can I just "log in" & install it or is it linked to my laptop/serial number.

OS X Mountain Lion Up-to-Date Program​

• The OS X Mountain Lion software content code must be used solely with the products that qualify for this offer.
• This offer is limited to one OS X Mountain Lion content code per qualifying computer purchased.

 

[Weaselboy]

I want to minimize clutter, fragmentation, lost files, system performance, & I think a clean install is the way to go unless this isn't an issue. Anyone?

Also, can I install Mountain Lion on my other laptop for free since my new Macbook Air is eligible for the Mountain Lion upgrade? Can I just "log in" & install it or is it linked to my laptop/serial number.

If your machine is working okay now, there really is no reason to go through the hassle of a fresh install.

After you get your activation code redeemed, Mountain Lion will show in the App Store app under your purchases and you can then download from there to a machine. It is linked to your AppleID and not a specific machine.