I know how to open it in photoshop but then what? haha
Here's how to reduce the size of the .tga's
1. Open in Photoshop
2. Go to Image -> Image Size
3. In the resulting window, look at the top field where you see the width & height dimensions
4. Enter in each of those fields one half the size of each .tga eg. 2048 goes to 1024
5. Make sure that the "Constrain Proportions" box that is in the bottom section of the window is checked. This will size the .tga appropriately in both width & height at the same time.
6. Hit "OK"
7. Save the file
8. Done!
I have an older version of Photoshop so if you have a newer version, the image size window may look a bit different but the gist of how to do it will still apply.