Adobe Photoshop PC for under £500

I'm looking to build a new PC to replace an aging system I have at the moment. I'm going to recyle a few parts (SATA Drives and DVD-RW) but replace everything else. I'm a bit out of date on the latest products and bets combinations so thought I'd post my intentions here for your thoughts.

It's primarily going to be a Photoshop CS4 and Lightroom 2 workhorse. I'm a photographer and spend a lot of time editing and often batch processing shots so need something quick for these applications. I'll be using XP initially until I can buy 64 bit Windows 7 and then I'll probably chuck in another 4GB of memory to speed it up further.

I'm in the UK and looking to buy from either Overclockers UK or Ebuyer.com and want to spend no more than £500 but ideally less. I've picked out the following components:

• AMD Phenom II X4 Quad Core 955 Black Edition 3.2GHz (Socket AM3) - Retail £149.99
• Sunbeam Core Contact Freezer CPU Cooler (Socket 754/939/940/AM2/AM3/LGA775) £28.99
• Gigabyte GA-MA770T-UD3P AMD 770 (Socket AM3) PCI-Express DDR3 Motherboard £76.99
• G.Skill Ripjaw 4GB (2x2GB) DDR3 PC3-12800C8 1600MHz Dual Channel Kit (F3-12800CL8D-4GBRM) £67.99
• Asus ATI Radeon HD 4870 Dark Knight 1024MB GDDR5 PCI-Express Graphics Card £119.99
• Antec 300 Three Hundred Ultimate Gaming Case - Black (No PSU) £45.99

Are these parts all compatible and are they the best for the money I have to spend? I want to try and stay future proof and may do a bit of gaming once I have a decent PC again. If there are any sensible alteratives that are cheapers but perform very closely to these then I'm open to change.

Thanks Hunter. I'll look at the saving I could make on the 4670 as I don't really do a lot if any gaming at the moment.

I've got an existing Antec TruePower Trio 650W PSU - With 3x 12v Rails and 120mm Fan but I'm not sure if this is compatible with the motherboard? If it is I'll use it to save a bit of cash but if not I'll check out your ideas.