vfpd: guess nothing wrong with your system above ..
Several things from me:
First, the monitor
You can consider to get 19" wide instead of 17". Samsung is good, before I was using Samsung for years (it was still old CRT monitor) until I decided to build a brand new system. When I got it the price difference of 17-19" is only about 15-20$. Which is in my point of view it's worthy. Esp. if you're planning for video / image editing. Bigger monitor the more convenience.
Second, vga:
Are you going to do massive work video editing or just home/personal editing? In the case of personal, that's fine
Third, processor:
See in the newegg, it cost around 50$. In this case, you should consider the x2 series like AMD Athlon 64 X2 3800+ Windsor 2.0GHz Socket AM2 65W Dual-Core Processor Model ADO3800IAA5CU - OEM in addition for arround 10$. The dual core will work better for video editing
Fourth, the ethernet adapter:
I'm not sure if you need to replace. The 100 means 100mbps? It will be depend on your DSL modem, if the port on your modem capability >>100mbps (1000 let's say) then it might good to replace it. But your new mobo already have gigabit LAN attached. So you don't need to buy separate card unless if you plan to do some router or bridge setting.
Cheers ^^