Premiere Elements is now up to version 8, as you noted. It has always been Adobe's policy to remove previous versions trial downloads.
If you have the trial download file, you can install it on a different computer and try it out for 30 days. If you do not have it, you are very likely out of luck.
The only way to install it on the computer, that had it before is to totally replace the HDD, install your OS and then install it again. Even then, there might be some problems. I'd try PrE 8 instead, as that is about all that you can legally buy now.
The link to download Premiere 7 is no longer on Adobe website.
I posted a working link to v7 Trial towards the end of http://forums.adobe.com/message/2303611#2303611. This is still currently valid, so grab it quickly before it disappears forever.
Insanity is hereditary, you get it from your children
I now recall your posting the link. I had forgotten about that. Nice going, and thanks for linking to it here.
Hope that it helps the OP.