Upgrade parts for photo editing

Hi,

I'm looking to upgrade parts of my computer and would like some suggestions please! I don't use it for gaming, just work and increasingly photo editing. The current set up is running slowly in Lightroom and Photoshop and has hung a couple of times so I think I need to upgrade parts.

I'm new to all this - first time replacing parts other then RAM - so I'd be grateful for any suggestions!

Many thanks in advance

Andrew

Answers to the template questions below:

APPROXIMATE PURCHASE DATE: as soon as possible

BUDGET RANGE: not sure - am open to suggestions. I have been looking more in the budget section of hardware guides on this site rather than the more expensive ones though to put it in context!

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: photo editing in photoshop and lightroom. I don't use it for games. Hopefully this will help keep the cost down (crossing fingers!)

PARTS NOT REQUIRED: list below

PREFERRED WEBSITE(S) FOR PARTS: dont mind - I'm UK based so will shop around
COUNTRY OF ORIGIN: UK

PARTS PREFERENCES: no preference - don't know enough about the differences between the different companies

OVERCLOCKING: No unless someone spells out in fool proof steps what I need to do...

SLI OR CROSSFIRE: I don't know what this is!

MONITOR RESOLUTION: details below, current monitor does HDMI

ADDITIONAL COMMENTS: quiet would be good! As described below, I would like to reuse my DDR2 memory if possible, appropriate and sensible. I have 6GB in DDR2 which should be more than enough so it would obviously save me some cash if I can reuse it. However, if this is a silly idea I'm open to being persuaded otherwise. I'm also intrigued by the USB3 talk as I do lots of USB transfers so (assuming USB3 on a motherboard will speed things up and it doesn't require special USB3 devices) this could be appealing.


This is what I currently have in my PC:

Windows 7 Professional 64 bit

Intel(R) Pentium(R) Dual CPU E2160 @ 1.80GHz

ASUS P5VD2-VM motherboard - http://www.asus.com/product.aspx?P_ID=2sYAtam7ng8vCngf

2 x DDR 2-5300 2GB. I also have 2 x 1GB DDR2 sticks which I'm not using as there isn't space in the motherboard. One issue here is that the motherboard will only recognise 3GB out of the 4 - nothing to do with 64bit OS, just the motherboard. ASUS forums recognise this as a limitation. http://vip.asus.com/forum/topic.aspx?board_id=1&model=P...

NVIDIA GeForce 9400 GT 512 MB

High Definition Audio Device and SB X-Fi Xtreme Audio

I have two hard drives (Maxtor 6L160M0 152GB and WDC WD5000A 465GB) plus a 1TB Buffalo LinkStation Mini NAS drive so I'm happy with all of this

I have a new BENQ G2222HDL monitor with DVI-D input so I also don't need this replaced

Speakers, mouse, keyboard I'm also fine with what I have

I think there's a 650W power supply and the case is a pretty large one.

Also randomly have a ASUS Silent Knight cooling fan - not quite sure why though!