Need some help with partitions...

I have my hard drive split into 2 partitions, with XP on the first and Win7 on the 2nd. I used EasyBCD for dual booting.

I don't use the XP anymore and want to delete that partition, and give the rest of the space back to Windows 7. I tried doing it in the Win7 Disk Management, but the option to delete the partition is faded out.

How do I go about doing that?

Thanks for your help.
EasyBCD > BCD Backup/Repair > Change boot drive

Move your boot files to your Windows 7 partition. Boot up Partition Wizard to delete XP's partition and extend Windows 7's partition.
I got startup repair to work, and now Win7 loads but when I log in - it loads a temp account and not much works.

I think part of the problem is that I had XP installed first, then installed Win7. XP had the C: partition and Win7 had the E: partition. When I deleted the XP partition and expanded the Win7 partition, I changed Win7 partition to use C:

I keep trying to set it back to E: in Partition Wizzard, but it goes back to C: every time?
You can't change the letter which Windows assigns at installation without breaking the OS (there are thousands of registry entries referencing it). It's no good trying to change it externally. Disk letters don't exist externally, they're just virtual labels held in the registry of the running system.
Luckily for you, Vista/7 allow you to get far enough into the OS to run regedit.
Use it to fix the problem and put W7 to what it was installed as.