Puppy isn't as light as DSL, but has substantially more in it. Also, if you're using that spec of hardware, I'm surprised you noticed any difference!!
with regards to the acpi=off comment - that's added to the kernel line in the boot loader. When the GRUB menu appears, press "e" and you can then edit the commands. add acpi=noacpi at the end of the kernel line.
whats the GRUB menu? i really dont understand why it wont install.