I've been using RaspyFi for a little more than a week now and first of all, good job and compliments to the developers!
External hdd (FAT32) connected and everything has been running almost flawlessly, except from a few mpd-crashes in the first few days.

As mpd-client I am using Cantata, a nicely looking client with lots of nice features. And one of the few to my knowledge that is able to edit tags.
Apparently some of my albums are, strangely enough, not properly tagged. To be able to edit tags I had to point Cantata to the physical address of the files which is 192.168.1.101\USB\usb1\MUSIC in my case, instead of Cantata's default folder "var/lib/mpd". But Cantata still cannot update the tags and I think it is because of read/write permissions.

Accessing the folder through Windows explorer shows that the folder is read-only and I cannot change this, nor the permissions in Windows. I also tried via PuttY as normal and root-user with the command "sudo -R 777 ." on the folder "/var/lib/mpd/music/USB/usb1/MUSIC". It still shows Read-only in Windows and Cantata is unable to write.
I think the folder "var/lib/.." is like a virtual folder within RaspyFi and I need to set permissions for the physical address. According to "fdisk -l" the hdd is "/dev/sda" but when I try to open I get permission denied in PuttY, both as normal and root user.

Any ideas how to set full read/write permission?

Sorry, indeed I did 'sudo chmod -R 777'.

Fstab gives me:

#
#/dev/mmcblk0p3 / ext4 noatime,discard,data=writeback,journal_async_c$
/dev/mmcblk0p3 / ext4 noatime, nouser,_xattr,errors=remount-ro 0 1
/dev/mmcblk0p1 /boot vfat utf8 0 0
Ramdisk /run/shm tmpfs defaults,size=256M,noexec,nodev,nosuid 0 $

I have no idea what this means? (except I don't see my 640 Gb hdd as a drive)

It's a Samsung G2 640Gb portable harddisk, bus powered, connected to the Pi through a powered USB hub. Disk is formatted in Fat32.
Pi is connected to the network with an Edimax Wifi-dongle. I use MPDroid on my phone and Cantata on my laptop to control it.

I think it is already mounted, since I could already access it with 'cd mnt/USB/usb1'. Also when I do 'sudo df -h' I see that device '/dev/sda1' is mounted on 'mnt/USB/usb1'. I tried the 'sudo chmod ..' on that folder, no luck. Cantata still cannot write to it and in Windows the files/folders are still Read-only.
When trying to mount it again it says "according to mtab, /dev/sda1 is already mounted on /mnt/USB/usb1/".
Also trying to set permissions as root user, no effect.

Now that I've tried setting the permissions I'll also check with the developer of Cantata to see if it might be a Cantata problem.