I presume you have tried to import them to the timeline and have received a message saying you need to activate or purchase a codec.
MEP 14 is no longer supported - it was released in March 2008 and is now 5 versions out of date.
Is your computer capable of handling HD video which is very processor intensive? - the Magix recommendation is:
Intel® Core™ 2 Quad-core processor - or AMD® Quad-core processor with 2.8 GHz
RAM: 4 GB. Dedicated graphics card with 512 MB VRAM or more. For accelerated AVCHD output: NVIDIA® GeForce® 8000 Series and better (CUDA™) or AMD® Radeon™ 5000 Series
and better (OpenCL™) or integrated graphics with Intel® Quick Sync Video
. . . . Upgrading my computer makes sense since it is 10 years. . . . .
That will lead you into a second problem if you upgrade and get Windows 8 - MEP 14 will not work correctly on Windows 8 - you would need to upgrade to MEP 2013.