[STS]

I recently had to buy a new computer. My old one had about 1600 photos on it, nearly all tagged or in tagged version sets, in PSE 3. I aked the shop to drag all my photos and documents across to the new hard-drive, which they did.
I wanted to use PSE 3 on my new computer but had to buy PSE 4 for it; when I imported the photos from the 'Old Files' folder which had been set up on the new PC, PSE 4 found the files and I then clicked on "Get photos". I was asked if I wanted to import all tags, so I clicked on "Yes", thinking that this was going rather well!
However, although all my photos are now showing in "All photos" in Organizer, only 177 tags have appeared, listed under "Imported Tags". What has happened to all the others? I know that not every single photo had an individual tag as some were in Version Sets, but I can easily see that lots of tags aren't now there. Even more oddly, some tags that are showing are earlier versions: I had some moth species listed as UnIDed but I'd later IDed them and had changed the tag accordingly.
Can I get around this by uninstalling PSE 4 and trying to re-import the photos.......with all their tags, I hope? Or can I delete the first attempt at importing and try again?
Unfortunately, the Windows file that the photos were dragged to does not show Adobe tags nor, presumably, can it cope with Version Sets. The fact that some tags came through on my first attempt is hopeful though??
Any help gratefully received and thanks in advance.
Thomas