Dell Studio 540 Upgrade

This is unknown brand, I really don't want to say anything bad, but the cheaper it gets the less reliability you can expect form PSU, can you return it, or it is already too late?

If you can return it, look here for recommendations about proper wattage for video card http://forum-en.msi.com/faq/article/power-requirements-for-graphics-cards
and look here for power supply ratings http://www.eggxpert.com/forums/thread/323050.aspx

I just want to say a few words about other components.
First, you PC is not overclockable, BIOS is locked, so no discussion here.
Second, you did not listed your CPU properly, you have Yorkfield Quad Core Q8200, 2.33G, 4MB, 1333FSB am I correct?

Next look at all processors compatible with your Studio:

MP627 Kentsfield Quad Core Q6700, 2.66G, 8MB, 1066FSB, G0
MP626 Kentsfield Quad Core Q6600, 2.4G, 8MB, 1066FSB, G0

N652J Yorkfield Quad Core Q9650, 3.0G, 12MB, 1333FSB, E0
F886J Yorkfield Quad Core Q9550, 2.83G, 12MB, 1333FSB, E0
C864D Yorkfield Quad Core Q9450, 2.66G, 12MB, 1333FSB, C1
N650J Yorkfield Quad Core Q9400, 2.66G, 6MB, 1333FSB, R0
C863D Yorkfield Quad Core QX9300, 2.5G, 6MB, 1333FSB, M1
80X97 Yorkfield Quad Core Q8400, 2.66, 4MB, 95W, R0
NH0D2 Yorkfield Quad Core Q8400S, 2.66, 4MB, 65W, R0
099K1 Yorkfield Quad Core Q8300, 2.5G, 4MB, 95W, R0
XVKFK Yorkfield Quad Core Q8200, 2.33GB, 4MB, 95W, R0
F824K Yorkfield Quad Core Q8200, 2.33G, 4MB, 1333FSB, M1

N654J Wolfdale Dual Core E8600, 3.33G, 6MB, 1333FSB, 65W, E0
D923J Wolfdale Dual Core E8500, 3.16G, 6MB, 1333FSB, 65W, E0
H399J Wolfdale Dual Core E8400, 3.0G, 6MB, 1333FSB, 65W, E0
K905F Wolfdale Dual Core E8300, 2.83G, 6MB, 1333FSB, 65W, C0
Y932C Wolfdale Dual Core E8200, 2.66G, 6MB, 1333FSB, 65W, C0
06YMG Wolfdale Dual Core E7600, 3.06, 3MB, 65W, R0
T116N Wolfdale Dual Core E7500, 2.93, 3MB, 65W, R0
K151N Wolfdale Dual Core E7400, 2.8G, 3MB, 65W, R0
Y442H Wolfdale Dual Core E7300, 2.66, 3MB, 65W, M0
X198G Wolfdale Dual Core E7200, 2.53, 3MB, FD, 65W, M0
9HP6Y Wolfdale Dual Core E6300, 2.8G, 2MB, 65W, R0
N807P Wolfdale Dual Core E5400, 2.7G, 2MB, 65W, R0
W3YMN Wolfdale Dual Core E5400, 2.7G, 2MB, 65W, R0
K212N Wolfdale Dual Core E5300, 2.6G, 2MB, 65W, R0
4HF4Y Wolfdale Dual Core E5300, 2.6G, 2MB, 65W, R0
YG8MC Wolfdale Dual Core E5200, 2.5G, 2MB, 65W, R0
T115K Wolfdale Dual Core E5200, 2.5G, 2MB, 65W, M0

Y933C Conroe E4700, 2.6G, 2MB, 800FSB, G0
CY593 Conroe Kit, E4600, 2.4G, 2MB, 800FSB, M0
T944D Conroe E2220, 2.4G, 1MB, 800FSB, M0
Y931C Conroe E2200, 2.20G, 1MB, 800FSB, M0
RX391 Conroe E2180, 2.0G, 1MB, 800FSB, M0
710PW Celeron Conroe E1600, 2.4, 512KB, M0

Prior to installing the processor, check that you have latest BIOS version installed.

I highlighted your processor and the strongest one tested to work in Studio 540, if someone advice to get something else, ask for the proof (I have one), discussions about what Intel recommends are not applicable to Dell PCs, since it is Dell who setup BIOS, not Intel...

Memory can be upgraded to 8 GB, if you have 64 bit Windows I would strongly advice to upgrade your RAM to 8 GB, 4 GB is not enough for Adobe - I have old PC with Adobe CS3 and 3.5 GB RAM (usable) and newer PC with CS6 and 8GB RAM, newer PC/Adobe setup beats old one everywhere.
Here general recommendations about memory DDR2 PC2-6400 • CL=6 • Unbuffered • NON-ECC • DDR2-800 • 1.8V http://www.crucial.com/store/listparts.aspx?model=Studio%20540 Crucial is the best brand for Dell, Corsair is second best, the rest are following.

Anything else I can help you with?