ext4 but not ext3??

I downloaded 5.2, verified the md5sum, burned it to a DVD at 2x, booted up Live, formatted the partition as 'ext3' and completed the installation but after the reboot and Grub, my install wouldn't boot... just a black screen after the Grub selection.

Tried again, this time selecting the Installer from the Boot Menu...but had the same result.

.....so I tried a 3rd time...but this time, I formatted the partition as 'ext4' and things couldn't be better!

Any idea why ext3 would not work but ext4 works fine? Since it's working wonderfully for me as ext4, I'm not going to change it...but I'm just curious why ext3 wouldn't work for me. I've tried several distros and really like Zorin....but this is the first time ext3 hasn't worked for an new installation.

I'm dual-booting with XP-SP3 on an older Compaq Presario 2170us with 1 Gig Ram, 80 Gig HDD (40 Gig for XP and 40 Gig for Linux), ATI Radeon.

Otherwise, this is a great distro!

Thanks!
El

Well, I don't want to discount the fact that my laptop is older (I updated the Ram and put a new HDD in it about 6 months ago) and it may be that the age of my laptop's video is the biggest factor; Gnome 3 simply won't run on this laptop at all ...... but Zorin is the ONLY distro I've tried where Compiz works right out of the gate on my laptop.