Get a different fan for the CPU. Stock fans have a tendancy to not even come close to cutting it, especially if you plan on overclocking your AMD.
Seagate. Good choice. Very good choice. I applaud your decision.

Get a CD-ROM/RW as well. Better thought, get a DVD-ROM/CD-RW. Then you can direct copy DVDs and CDs instead of having to rip them then burn them.
Can of air! You can get those at most supermarkets, but by George are they handy!
Now, if you're going for heavier photo manipulation and video editing, grab another stick of 1GB RAM. 1GB is the bare minimum these days, and 1.5 passes pretty well if you just plan on doing some gaming. Since you said you like Photoshop and Dreamweaver a lot, grab that extra stick up now. You won't regret it. (Do
not grab a dual-channel 2GB stick. Those are unstable as hell and are more likely to cause crashes than they are to prevent lag issues.)