Can someone explain for me what is meant by
rootnoverify (hda,4)
chainloader + 1

This is used to boot a windows operating system. I don't really know why it is so. But rootnoverify (hda,4) is wrong, it should be rootnoverify (hd0,4) as grub uses different harddisk labeling and partition labeling. hda is in fdisk the primary harddisk. When in grub it is hd0. Well to get back to rootnoverify (hd0,4). This means that you want to make the 5th partition on your primary harddisk to be made root and boot from it.

chainloader +1
I don't really know what this stands for. But it is only used in booting Windows. So maybe someone lese could comment on that.

"chainloader +1" is actually the type of booting grub is instructed to do. Grub is set up to boot several different types of things. Chainloader is the most simplistic. Basically it means, "grab the first sector off the root device and run it". This is exactly what BIOS does when it loads a boot loader. You could have:

BIOS loads grub stage1 from the mbr
grub stage1 loads stage 2
grub stage2 loads lilo hiding out in another distro's partition
lilo loads the MS boot loader (NTLDR etc.) from the microsoft partition
NTLDR loads windows
etc

You can see why it might be described a chainloading (Note, you don't need to use grub/lilo in this fashion, but you could). You could literally install grub 20 times on a drive, and use chainloader to jump between them (not that this would accomplish anything).

Hi,
Thank you guys, I understand it a bit more, am saving this info for future reference.