Some approaches:
IF your media files will be on the same volume on the new PC (eg C drive or same NAS)
Option 1
1. Generate a full backup of your library on the MC26 install - File>Library>Backup Library
2. Copy all the media files (and any associated sidecar and cover art jpg files to exactly the same volume and folder structure on the new PC.
3. Install MC28 and make sure you terminate the 'auto media search' that pops up in the Action Window on first startup.
4. Restore the MC26 backup from Step 1 to your new MC28. File>Library>Restore Library
Option 2
1. Install MC28 on the old PC and and let it do it's upgrade magic on MC26.
3. Generate a MC28 backup (include thumbnails) from the new install.
4. Follow the rest of procedure as above but restore the MC28 backup from the old PC.
IF your media files volume and folder structure are going to be different on your new PC
1. Copy the media files as above
2. Install MC28 and let it generate a whole new library e.g. Let 'auto media search' run on first startup.
I would strongly recommend Option 2 as:
1. Although it means installing MC28 twice, you get the chance to check out MC28 without the 'unknowns' of having moved to a new PC.
2. The thumbnails get moved to your new PC so saving having to generate them again. I have no idea how big your library is but it can take significant time to generate new thumbnails on a large library.
Terry
EDIT:
BTW Harry if you are a luddite shouldn't I be proffering you advice on how to upgrade your card index for your gramophone or phonograph collection?
'Sorry Ned, can't come to the loom smashing tonight, I've just taken delivery of a 'Spinning Jenny' and it is taking longer to setup than I expected'........