i tried ubuntu 11, on installation it gives only two options either erase windows 7 or something else. if i put something else it comes with partitions and drives. i have 3 drives 240gb for two and 20gb for one. however i select drives it gives error as no root file system defined. iam new to ubuntu can anyone pleae tell me clearly how to proceed

The "something else" refers to manual partitioning. The Ubuntu installer used to just call it manual partitioning, but people were starting to get used to that. So the Ubuntu developers decided to change it to the more cryptic "something else"
When choosing manual partitioning you have to create the partitions, assign the file system for each, the size of each partition, and the mount point. You need to create at least 2 partitions, one for root and one for swap. Ideally you should create a 3rd partition for your home directory for your data.
Here is a great site with tutorials for dual booting Ubuntu and Windows7: http://members.iinet.net.au/~herman546/ On that site the "Graphical Installation 'A'" covers dual booting Ubuntu and Windows on separate hard disks. It covers partitioning also.
Here is another tutorial on manual partitioning: http://www.psychocats.net/ubuntu/installseparatehome
Write back if you need more help.
And welcome to the LQ forums!

great thanks so much i ll try and let u know

hi i tried as suggested but iwas not able to clear the first step. thi is how my partition looked.
dev/sda
dev/sda1 1mb
dev/sda2 nfts 208mb
dev/sda3 nfts 255222
dev/sda4 nfts 244674
i tried sda4 and clicked change and repartion size to 124674 and clicked ok then one confirmation box asked to continue i clicked continue but it comes error msg as resize operation failure. what should i do. please help

Boot to the live session on your LiveCD.

Go to System>Administration>Gparted Partition Editor (name may be different but similar - I am on Debian).

Resize the Win JerryLewis Pro partitions from there and create your partitions there and then do your install. This is much easier and more reliable than the installer partitioner.

If these 4 partitions are all primary partitions then that is your problem. If you have 4 primary partitions you can not create any more partitions since 4 primary partitions is the limit. What is that 1mb partition on /dev/sda1? I would think that that the 208mb partition on /dev/sda2 would be the Windows7 boot partition. Is that correct? I do not know why you have that 1 mb partition on /dev/sda1.

I would think (although I can not be 100% sure) that if you want Ubuntu on /dev/sda, then you should delete /dev/sda1. Then resize either /dev/sda3 or /dev/sda4 to make room for 2 or more logical partitions for Ubuntu.

From the Ubuntu live CD, open a terminal and post the output of:
EDIT: Since you have 3 hard drives, where do you want to put Ubuntu???
Post the output of sudo fdisk -l. Then tell us what you want to do and where you want to put Ubuntu.

hi as shown initially i had only c and d(recovery). later i partitioned c using windows into c and f, 240 gb each. but later automatically another one got added which is q 1mb named microsoft office click to run 2010 protected. i think its probably after i installed office 2010. i was not able to delete it r open it. and properties show 0bytes for q.
ok here is what i got after using your command.
disk/dev/sda: 500.1gb
255 heads, 63 sectors/track, 60801 cylinders
units= cylinders of 16065$512= 8225280 bytes
sector size logical/physical 512/512 bytes
device boot start end blocks id system
/dev/sda1 1 1 992+ 42 sfs
partition 1 doesnot end on cylinder boundry
/dev/sda2 1 26 203776 42 sfs
partition 2 doesnot end on cylinder boundry
/dev/sda3 26 31055 249240576 42 sfs
/dev/sda4 31055 60802 238940184 42 sfs
this is whT I got.
i want to have my linux partitioned from f drive since i have windows in c. shall i partition f drive with windows and then install ubuntu in it. i think it should be done by selecting / in newly created one, is it correct. what should i do. the first link u gave was very helpful to understand installation, thanks. help me what to do. and how to get that q drive with windows out.....