I spent a few days making research to make sure they are compatible and would it be possible for someone to tell me of any incompatibilies? I wouldn't be pleased to find out that a component won't work with that setup. I will be using it mainly for software development and for TV show recording.
Motherboard? I don't have any expierence with Biostar so I couldn't say if it's a good brand or not, but 945p chipset, you could be buying alot worse. It's definitely a decent chipset, and most likely a good board. $93.99 (tigerdirect)
Memory? The stuff you listed sounds pretty cheap, and you can get good ram without spending alot at all, nowadays. THIS is some awesome ram, 40$ off, you get dual channel, tighter timings then the cheap stuff, good quality brand name, yes, for $40 more, but you wont regret it. Cheaping out on memory, most likely, means an unstable system. Spending less is good, but spending the least isn't.
CPU? The Pentium D 640 is, the cheapest I could find, 153$. The Pentium D 805 (dual core) may have a slower clock speed (2.66ghz) but it has 2 cores, multitasking, video editing, newer games will all run faster on this thing then the 640.
Harddrive? Looks good, Maxtor is a reputable brand, although I personally believe Seagate and Western Digital are better. Just make sure you buy the 16mb cache. Just so you know Maxtor makes the loudest harddrives out of the three manufactorers. Maxtor 250gb SATA2 16mb
I'll leave case up to you, just make sure if your going to use the cheapy power supply that comes with most cases (not recommended), make sure you buy at least 450watt. Although the Antex Sonata II case is your best bet as it comes with a high quality 430 watt psu, in a sleak, quite, quality case.
Also you didn't mention videocard. Your motherboard doesn't have onboard video, and if you want to spend least, I still recommending getting a newer, low end card. THIS card would fit that bill. And only $38.99.
If you got the better ram and processor you only spend 20$ more for a much faster and stable system.