I'm trying to install ubuntu but i already have windows 7 on the same computer and i can't afford losing it. everything went perfectly well until allocating drivespace. i dont have the option to "install it besides another operating system " like in the instructions. i only get this menu when my external hard disk is plugged in, but i dont want that. any help assigning partitions? because i have no clue about what to do there this is what the partition menu gives
To answer more Allocating drive space?, you will need to provide how many windows partitions are there. Refer this documentation on disk partitioning.
Refer to the section which says how to resize from windows 7 and try that. Else, report the number of partition reported as per 'Settings -> Control Panel -> Administrative Tools -> Computer Management -> Storage -> Disk Management' in windows 7 and type of these partitions (meaning primary vs extended or any other type).
The reasons would be more likely, Maximum possible primary partitions that is 4 primary partitions are already defined and allocated for windows. I see this in many MNC brand laptops and it is a very poor partitioning scheme. In that case, you will need to delete one of such primary partition and create an extended partition. You can shrink another existing partition as well and add to this free space if you are able to get contiguous space. Once you have extended partitions/free space created, Ubuntu install will show optin to install along side with windows 7.
There are other possibilities, but probably hearing from you more on your current windows 7 partition types and number of partitions can help if we need to discus those options.
If your entire disk is already devoted to your windows partition, re-partitioning that drive is risky at best. For me, the ideal way has always been to install side-by-side is to install windows first, but specify that the partition that is created only takes up half the drive or whatever. Then when you install ubuntu, you install it in the unpartitioned space left over.
The safest thing if you're worried about your existing data and install, is to use Wubi. This allows you to install ubuntu directly to your windows partition, but in a way that makes it look to Ubuntu that it's in its own partition. It's pretty cool, but the drawback is supposedly that disk access would be slower, hence Ubuntu would appear slower. Personally, I haven't noticed that much of a difference, but I'm sure it's there.
Either way, backups are highly recommended before you proceed.