I just wanted to concur that my own experiences have shown that the OS install, itself, and any software installations thereafter will inherently leave fragmentation on your hdd. It's not the drive's fault. Once you have all your stuff installed, defragment, and you should find the fragmenting thereon should be more typical to your regular use experiences.
I also suspect that the impact of fragmentation is highly overrated. I'm not saying you shouldn't defragment occasionally on a Windows machine. Occasional short sessions should be less invasive than one giant session after waiting for fragmentation gets so bad the wheels are falling off.
I just mean to say that when you see the fragmentation report, don't get freaked out so quickly, even if you see a good amount of red. It looks nasty, but I suspect it can be allowed to get much, much worse, before there is any real performance impact on the system.
I think once you got all the main OS parts and software in good shape, they should stay that way on their own, and the only thing left to get fragmented are a group of temp files and maybe some frequently moved/copied files. That stuff could tolerate getting chopped up real good, before there is a significant system impact. It may look bad on the defrag report, but it's probably not as serious as it looks. It's still good to keep them spiffed up regularly, but just don't get freaked out if they happen to be a bit straggley when you check.