Windows 7 installs usually use all 4 primary partitions. You may have a hidden Boot partition.
My laptop already has 4 primary partitions: how can I install Ubuntu?
Good advice on how to handle all four primary partitions used. - srs5694
Be sure to create recovery DVD(s) first. And a Windows repair CD.
Windows always needs a chkdsk after any resize. Best to use Windows own tools or Windows third party tools to resize Windows. Then immediately reboot so it can run chkdsk. NTFS partition have data in the NTFS partition boot sector on the start & size of NTFS partition and that must match partition table. Chkdsk updates that info.
Do not create new partitions with Windows, it may convert to dynamic partitions which are Windows proprietary and do not work with Linux.
How you set up partitions depends a lot on how you are going to use system. I tend to like smaller system partitions for both Windows & Ubuntu and larger data partitions. But I like to install the next Ubuntu to see if it works on my system while keeping current working install, so I have several / partitions.
For the Total space you want for Ubuntu:
Ubuntu's standard install is just / (root) & swap, but it is better to add another partition for /home if allocating over 30GB.:
Only if gpt - all partitions in gpt are primary:
gpt: 300 MB efi FAT32 w/boot flag (for UEFI boot or future use for UEFI, you only can have one per drive, so if already existing do not attempt another)
gpt: 1 MB No Format w/bios_grub flag (for BIOS boot not required for UEFI)
for gpt(GUID) or MBR(msdos) partitioning
Ubuntu partitions - smaller root only where hard drive space is limited.
If total space less than about 30GB just use / not separate /home or standard install.
1. 10-25 GB Mountpoint / primary or logical beginning ext4(or ext3)
2. all but 2 GB Mountpoint /home logical beginning ext4(or ext3)
3. 2 GB Mountpoint swap logical
Depending on how much memory you have you may not absolutely need swap but having some is still recommended. I do not hibernate (boots fast enough for me) but if hibernating then you need swap equal to RAM in GiB not GB. And if dual booting with windows a shared NTFS partition is also recommended. But you usually cannot create that as part of the install, just leave some space. Or partition in advance (recommended).
One advantage of partitioning in advance is that the installer will use the swap space to speed up the install. Thanks Herman for the tip.
suggested partitions for just Ubuntu on 3TB drive.
Another advanced suggestion from TheFu with Multiple / (root) - Post #5 similar to what I actually do