..........and I don't wanna resize the partitions with Gparted(I have tried it, and I had problems)
I do this about once a month
and have no problems if you do one thing at a time.
Also, I use the live CD
Just yesterday, I re-sized 2 data partitions of about 200Gb, deleted a partition located before these ones, re-sized the one next to it to fill the empty space and created a 100Gb partition at the end of the HD.
No problem at all. But.....one thing at the time...no batch work.
As you stated that you have Win7 and Pclos on that drive, I assume you tried to move/resize the Pclos psrtition, using Gparted in Pclos....That doesn't work.
You have to use the LiveCD in this case, or resize from within Win7
If my assumption was wrong, please pardon me
If you still don't want to try, and buy a 2nd HD, I would keep the first one for windows and the second one for Linux.
You still can use the space on the first one to store data.
Just my 2 cents