Need advice: RAM vs HDD Upgrade

[StopSign24]

I currently have a Late '09 13" Macbook Pro 2.2ghz upgraded to 4gb of RAM and a 320gb 7200rpm HDD.

I have some extra cash, and have decided that I want to upgrade one of these to either 8gb of RAM or a Momentus XT 500gb HDD.

I do a lot of work in Photoshop and Illustrator, and was wondering which would be a better upgrade, as I can only do one.

The Momentus is $115, while the RAM is $180.

Thanks.

 

[0007776]

Does your computer run slow to the point where you would benefit from more RAM? Since you have to ask about this I would guess that you'll get more benifit out of a larger HD than more RAM.

 

[StopSign24]

Does your computer run slow to the point where you would benefit from more RAM? Since you have to ask about this I would guess that you'll get more benifit out of a larger HD than more RAM.

Sometimes it does, mostly when I have both Illustrator and Photoshop open and are switching between the two frequently.

HDD space isn't really an issue for me, it was more the transfer speeds that I was interested in.

Edit: After doing some more research, and turning on the efficiency monitor in Photoshop while working in both Illustrator and Photoshop, I've come to the conclusion that more memory would be redundant. The HDD it is.