[ubuntu] GParted-Partition Question--Want to merge partitions to increase space

Background:

I have a dual-boot with Windows XP/Ubuntu Lynx 12.04. Gparted shows that my 320 GB (?) hard drive is partitioned as follows and in this order from left to right:

/dev/sda 1 97.5 GB (this contains windows XP and files) File system fat32
/dev/sda 7 100.47 GB (empty) File system ext4
/deve/sda 5 97.18 GB (this is where all my file and Ubuntu are located) File system ext4

There is also a small 3.2 GB swap partition at the very end.

Issue/problem:

I would like to merge sda7 and sda5 as I am running out of space in sda 5.

However, the Gparted Resize/Move option is not active when I rightclick on sda 5.

I also cannot unmount sda 5, I get this message: Most likely other partitions are also mounted on these mount points. You are advised to unmount them manually. Not sure if that needs to be done, just letting you know. sda7 is umounted.

I screwed around with Gparted a bit last night and woke up to find Grub> when I rebooted my computer. Miraculously I was able to access the Internet on my cell phone to fix that, and the computer now reboots to Ubuntu as previously and everything is working well.

Although I have been using Ubuntu for more than 4 years, it should be obvious that I am pretty much a neophyte, so if you have any solutions pleases bear that in mind when explaining!

Thanks in advance for any assistance.