I started out with Photoshop CS, the first CS version, and I tried to teach myself. OMG what a nightmare! A friend's husband was using it but strictly as a semi-pro photographer. I soon realized that 1. it was going to be too hard to learn for what I wanted to do...play with what i finally learned was scrapbooking! and 2. I was not interested in making my photos look professional/perfect etc.
I switched to the Mac PSE4 which was the only one out at that time, and now have PSE10. Because I got such a good deal on 10..like $40 at Costco incl the Linda Sattgast dvd on PSE10...I got it but all in all I was happy enough with PSE9.
Do you want to write your own actions? do you want lots of text on a path options? Do you seriously want to work on your photos beyond what PSE can do? Do you want to start learning a new program? Lightroom has its own learning curve and it is my not so humble opinion that Adobe software is the least intuitive I have ever learned. ymmv but that's how it's been for me.
I guess Laurie, I'd ask yourself where you want to go in scrapping. Do you want to design more things? or do you want to scrap more? Going with CS5 will give you opportunities for the former but you will have to take a great deal of time from the latter to learn it, and unlearn some of your PSE methods. That's my take each time I see a sale 'too good to miss.'