H.264 isn't really "Problematic" on windows. Some containers aren't read by some software and it can be a load on a system if the CPU is slow and memory is low. The system needs to meet the spec's of the software as far as CPU speed and RAM. Also some software is capable of GPU acceleration and that speeds up the use of H.264, especially when using AVCHD.
If your system will handle it, try the latest version of Da Vinci Resolve lite can do alot and you can download the Gopro studio, both are free. If the file extension reads .mp4 both will read it. If they read MTS or M2TS then you will need to convert but there are some free options for that as well. So you can mess around with it some before buying a NLE to see how your system will handle editing. But look at the system spec's of the software and make sure you meet it or you will deal with things like crashes and such.
