Thermaltake Element G

Personally, I'd go with the HAF 922 instead.

Your GTX275 has a lendgh of 10,5inch ( http://www.nvidia.com/object/product_geforce_gtx_275_us... ) and this case supports that lendgh as you can see in the vidio below.

If you like it, go for it. It's a high quality midtower with a lot of features.
However it have some weakpoints:

No side panel window, not even an optional one
No anti-vibration mechanisms for the HDs.
No eSATA and FireWire port.
No meshed covers on all expansion slots.
No dust filter on the side panel fan.
Covers from water-cooling holes need to be broken.

If you don't mind these little issues, go for it. it's a fantastic case.

Here you have a video review:

http://www.youtube.com/watch?v=uFg1JluB8hI

Other good options are:

COOLER MASTER Storm Sniper Black Edition:

http://www.youtube.com/watch?v=QEzAGW-T-Zg

ANTEC 902

http://www.youtube.com/watch?v=e-igk9kT2P8

Lian Li PC-7FW

http://www.youtube.com/watch?v=9FtBh8FFvZM

Thanks for the replays guys but I have a few problems with other cases you mentioned because they are big. The length of the case that I can put is only up to around 53cm and the Element G is 52cm so it fits very good while both the Sniper and the HAF 922 are around 56cm which isn't good to me.
What do you think I should do? Go for the Element G or pick other one?

Thanks

Go for the THERMALTAKE Element G. It's a very good case. You won't be disappointed at all.

Are you sure the Element G has enough inner space or is it too small?

Yes, I'm sure. You won't have any problem with your gtx275.

Here you have a video where a guy shows his computer. He has a GTX275 in a THERMALTAKE Element G.

http://www.youtube.com/watch?v=as9iNPNiY4E (turn off the sound, the music is awful)

Thank you so much, you really saved me with this video