The best way to fix this problem is to reduce the number of partitions by extending C:
His original post said that he'd just finished shrinking C. I'm sure he doesn't want to extend it back.
He just wanted to make a new partition on his drive, and did not know about the true essential difference and consequences of "primary" vs. "logical", and what happens when you do partition restructuring.
you're only allowed 4 partitions on a single drive.
Not true. You are only allowed FOUR PRIMARY PARTITIONS on a single drive.... not four TOTAL partitions.
If one of those four "primary" partitions is treated as an "extended partition", then you can now sub-define ANY NUMBER OF "LOGICAL" PARTITIONS inside of that one "extended partition".
So in this latter arrangement, you are limited to THREE PRIMARY PARTITIONS that get their own drive letters, and then you can have 1-to-n "logical" partitions sub-defined within the fourth "primary partition", i.e. the 'extended partition", with each of those "logical" partitions then getting its own drive letter.
In fact, other than on the BIOS-set "hard disk #1" boot drive, no other hard drive needs ANY real "primary" partitions. You could define nothing but one "extended partition" on every one of your secondary hard drives, and then nothing but "logical" partitions inside of every one of those "extended partitions".
You don't really need "primary" for any partition other than the "active" partition on "hard disk #1". Even the Win7 system boot partition can be "logical" (say, in a "logical" partition on a second hard drive... different from the WinXP boot partition on your primary hard drive, for example if you install Win7 as a second OS on an existing WinXP machine and had added a second hard drive for it plus more data).
In fact, Win7 installed as a second OS on the SAME "hard disk #1" as WinXP is already installed on can go into a "logical" partition on that same hard drive. It doesn't have to be in a primary partition. Again, only the "active' partition on "hard disk #1" is required to be "primary" for Windows. Everything else can be in a "logical" partition, which therefore allows MAXIMUM FLEXIBILITY in terms of partitioning now or in the future.
For example:
WinXP is on O (active) above, and Win7 is on C.