Failed to open stream: Permission denied in… (image upload)

Hi, I just moved my blog to a new domain (on the same server, using Mediatemple, alternate domains.) Posting and everything goes just fine but uploading images give me this warning:

Warning : copy(/home/virtual/site406/fst/var/www/html/apuntesgraficos.com/wp-content/saville.jpg): failed to open stream: Permission denied in /home/virtual/site406/fst/var/www/html/apuntesgraficos.com/wp-admin/upload.php on line 170
Couldn’t upload your file to /home/virtual/site406/fst/var/www/html/apuntesgraficos.com/wp-content/saville.jpg.

After browsing the forums I see that this probably got to do with permissions, but I don’t understand what I should change, I’m using version 1.5.

Grateful for any help