As far as I can see, you have reached the maximum number of primary partitions. Unfortunately you can't have more than four. For more info you can read here and here.
If you want to have a greater number of partitions, you should delete one of the existing ones (but I don't know your machine and I'm not a Win7 user, so I can't tell you which ones are safe to delete and which one must be kept cause are required to Win) and create an extended partition, that basically acts as a "partition container" where you can have inside the number of logical partitions that you require.
As an example, have a look at my personal disk configuration:
And as you can see, I'm in a situation similar to yours. The partitions sda1, sda2 and sda3 are used by WindowsXP; I had to make sda4 an extended partition, because this allows me to create additional ones inside it; sda5 and sda6 are used by Linux, and sda7, also used by Linux is set as swap.
Like I said, I don't know your machine and neither Win7 thus I can't say "delete this" or "delete that", but I can see that your sda2 partition is a NTFS smaller than 1MB. You can try to investigate if it has some role on Win7 or if it can be safely deleted.