Multi-use partial upgrade ±$400

[Krakpot]

1. What YOUR PC will be used for.
Light gaming (10-14 y-o boys, NO FPS), photo & video editing, MS-Office duties.

2. What YOUR budget is.
±$400

3. What country YOU will be buying YOUR parts from.
Canada / Quebec

4. IF YOU have a brand preference. That means, are you an Intel-Fanboy, AMD-Fanboy, ATI-Fanboy, nVidia-Fanboy, Seagate-Fanboy, WD-Fanboy, etc, etc, etc, you get the picture.
For this build, prefer high price/performance ratio CPU/ATI/G.Skill or Corsair/Seagate or WD

5. If YOU intend on using any of YOUR current parts, and if so, what those parts are.
Antec case w/ Antec SmartPower 400w
NEC DVD writer
Creative Audigy 2 audio card (if necessary)
DELL 2209WA IPS + DELL 1907FP TFT dual setup
Keyboard, mouse, speakers
Windows 7 Home Premium 64-bit

6. IF YOU have searched and/or read similar threads.
Have been shopping for weeks on multiple forums and online stores, have built several PCs over the years.

7. IF YOU plan on overclocking or run the system at default speeds.
Don't plan on overclocking

8. WHEN do you plan to build it?
Will order parts within 1 week

9. What resolution do you use?
1680 x 1050 (primary monitor + gaming) & 1280 x 1024 (secondary monitor)

I've been considering the following components for a low-cost upgrade to replace an aging (!) P4-2.66+Radeon X850XTPE. Prices are from bestdirect.ca but will also compare with the usual NCIX/Newegg/others. I've dealt with NCIX with good results in the past.

AMD Athlon II X4 630 $99.79
ASUS M4A78LT-M LE AM3 780L $67.30 or ASRock M3A770DE AM3 770 $64.99 (Newegg only)
G.Skill F3-12800CL7D-4GBRM CL7-8-7-24 $125.58
Seagate 7200.12 500Gb $39.79 or WD Caviar Black 640Gb $59.79
Gigabyte Radeon 4670 $77.13 - $10 MIR

-- Totally unsure about the motherboard, don't need anything fancy but want AM3 & DDR3
-- DDR3 4Gb, want the same RAM as my $1000 build in separate thread, easy upgrade later if needed!

Thanks in advance for your input, can't wait to upgrade !

[_dangtx_]

looking good. rams a tad expensive for 4 gigs. psu wise, a nicel ittle 400 watter will be good for this light system.

[rapmaster]

Yup look good, nothing I would change.

[gingerbee]

looks good to me i would drop the asrock just had bad luck with them. jmo

[Krakpot]

looking good. rams a tad expensive for 4 gigs

I agree the selected ram is not the cheapest, but I want the same as my $1000 build in the other thread, this way I can increase it later to 8Gb if necessary with the exact same ram...

I often see the G.Skill F3-12800CL9D-4XXXX suggested at ±$120 but not the CL7D at ±$125, any reason why ? Seems to me the more agressive timings at the same approx. price makes sense...

I will drop the ASRock, don't want to buy at two separate shops if I don't have to.

Thanks for all your comments.