Is it worth upgrading anything for £50 or should I maybe buy a new mouse or even just keep it 
Full spec is :
i5 2500k
Gigabyte P67-UD3
OCZ 600W
GTX 580 1536MB
Artic Cooler Freezer 7
Zalman Z9
Seagate Barracuda 500gb
Samsung Spinpoint F3 750gb
LG DVD-RW
Microsoft Sidewinder X4
Logitech MX518
OCZ Special OPS 4GB
Think thats everything tell me if I missed something.
I was thinking either Blu-ray drive, 8GB Ram or CPU Cooler?
Any suggestions
Edit: or perhaps a Razer Deathadder.

Full spec is :
i5 2500k
Gigabyte P67-UD3
OCZ 600W
GTX 580 1536MB
Artic Cooler Freezer 7
Zalman Z9
Seagate Barracuda 500gb
Samsung Spinpoint F3 750gb
LG DVD-RW
Microsoft Sidewinder X4
Logitech MX518
OCZ Special OPS 4GB
Think thats everything tell me if I missed something.
I was thinking either Blu-ray drive, 8GB Ram or CPU Cooler?
Any suggestions

Edit: or perhaps a Razer Deathadder.