This is just a notice of warning to everybody on this list who considers buying Adobe's Creative Suite.
When Adobe came up with the first creative suite (CS1), they made it very easy and attractive for all Photoshop users to buy into an entire suite for a relatively cheap price. Naturally, that way, they demonstrated that they had a very good sense of marketing their products. Nothing wrong with that, of course. So, I took advantage of their offer and I upgraded from Photoshop (single application) to the Creative Suite. Now, when the economy got tough, I wanted to go from the entire suite (CS3) to a single application (Photoshop CS4). After all, having the suite is nice and sometimes needed, but having the Photoshop is a must.
So, I went to Adobe's online shop, I checked my eligibility status, which turned out to be OK and I placed my order without any warning flag along the way. Then, when I installed Photoshop CS4, it did not want to accept my serial number. I contacted Adobe and it turned out that, in fact, I was
not eligible for a 'sidegrade' from an entire suite to a single application. I repeat, there was no warning on Adobe's site.
So, basically, Adobe trapped me for life into buying an entire suite of applications that I rarely or never used. If I wanted to go back to a single application, I had to pay the full price of this application, even though I already paid the full price for an original retail version before buying into the suite. This is a kind of practice that I am comfortable to compare with the practices of pirates who steal their software without any payment whatsoever. Adobe, you just proved that you deserve to be pirated...

I cancelled my order, had to send them a "letter of software destruction" and received a refund (in about 2 weeks).