The memory is pretty low, the video GPU is very basic. You'll tax the 80GB space so in every dimension this is one small computer.

Did you check the top 100 list at Amazon.com for 300 buck models that are new and have more RAM and disk space.

Here's the link ->
http://www.amazon.com/Best-Sellers-Computers-Accessories-Laptop/zgbs/pc/565108

I see machines near 300 that have a lot more RAM and disk space and might be faster at that video editing.

As to iMovie on a Windows PC. No.
Bob