Week 39 and later Bartons are supposedly multiplier locked. The date code (week and year) are in the center of the lower string of digits on the sticker placed on the CPU. Regardless, this is only important if you plan on doing serious overclocking.
I also notice the high performance PC3200 (DDR400) memory. Unless you plan on doing some FSB overclocking, PC2700 is all you need, as the 2500 - 2800+ are all 333 FSB parts. In fact, if you run the DDR400 at 400 speeds you will lose a tiny amount of performance using anything less than a 3000+ (400 MHz fsb part). If you plan on overclocking or tweaking the memory timings, the PC3200 is a good choice, but otherwise you can save some money and choose PC2700 instead.
On the casefans, Vantec Stealth fans are very quiet if that matters to you.
The processor heatsink you picked is the one I have on my (overclocked to 2.2 GHz) 2400+ CPU in my primary computer. It is a good heatsink, but quite a bit louder (though not annoyingly so) than the retail box heatsink. Unless you plan on overclocking, AMDs retail box heatsinks have been improved a lot recently and are fine for the CPU they came with running at stock speed. Since you are buying the retail box CPU (which comes with the heatsink and fan), you don't actually need the Vantec Aeroflow (unless you want to overclock).
Overall I think you made pretty good choices. As I said though, a couple of the parts you picked are only useful if you plan on overclocking. (The DDR400 memory would also be useful if you plan on upgrading the CPU to a 3000+ or 3200+ at a later date.)
