If you use Gparted on openSUSE (rather than on a CD) you will find sda4, sda5 and sda6 locked and not able to be resized. This is because they're in use (mounted) when openSUSE is running.
You can't resize partitions with the windows xp partitioner.
Download the CD.iso image from Gparted website and burn it to a CD in openSUSE then boot off that. Probably no partitions will be locked. But possibly the swap partition sda6 might be locked (highly unlikely). If swap sda6 is locked, you can R-click and select to turn the swap partition off. Then nothing will be locked and you can proceed.
So let's summarise your options:
- delete Linux, shrink the windows partitions with Gparted on CD and then reinstall Linux in the space that is made available.
- move the files on sda3 over to sda2 and delete sda3, sda4, sda5 and sda6 and reinstall Linux in the space that is made available
- shrink the and move the existing partitions as I have advocated with Gparted
Regarding option 2, deleting sda3, the My Docs partition in Windows, as recommended by caf4926: If you decide to go that way, you should move the My Docs (or probably it's the Docs and Settings full deal) directory first to the drive sda2 using a special method that involves the registry settings. Don't just move the files and then delete the partition. That would break windows.
Which is the best way to go? IMO all three options are viable. You sound like an adventurous user but inexperienced in the partitioning field. The risk of mistakes is therefore high. So I would recommend option 1 first, option 3 second and option 2 third. Just my opinion and with full respect to caf4926.