Alright, Salaris, here's what I see from what you've picked. You've definitely got some great choices overall, so here're the pros and cons of each (in my opinion, of course):
Excellent overall. I don't see any cons to this machine, though there are some things I see better on the others. But as a computer overall, this is a great choice. You've got a 7200 RPM for the hard drive, which you're definitely going to want. Don't downgrade to the 5400 RPM. You'll regret that, unless money there is really an option.
The bluetooth is another excellent feature, although you'll only really use it if you're big into making ringtones and such. It can be used for a gazillion other things, but that's generally the most popular use.
This one has some great features, and almost makes me want to lean toward it as the top machine you're looking at. But there are reasons I tend to shy away from it. Let me point out what's good about it, and then go back to why I might not go with it. Since it would be your choice in the end.
You're getting a better video card, and a bigger hard drive. Both very great improvements over the Sony. The thing about the video card that really catches my attention, though, is the 1GB memory. That's going to greatly improve your games over the 512MB memory. However, don't let that be a deciding factor, because the 512MB is still going to be a great card. Remember not to let single things tip the balance. Keep everything in perspective. You would just have, say, a harder time playing TFU on the PC than the 1GB would.
The thing you want to be careful with HPs is just that they tend to produce en masse. And, as such, they tend to produce low quality products overall. I've had an HP that I absolutely loved, but typically (and especially more recently), I find that their products aren't all that lovingly made. They have glaring errors like the touchpad or the keyboard, major components of a laptop, as you know. But...that's just my opinion.
I wouldn't really consider this one. While you're getting a better video card, you're getting a worse hard drive, which I, personally, would not want to do. Remember that all components of a computer feed off of each other. While you may have an awesome video card, having a slow hard drive is going to counteract that. Not always, but typically. The wireless card is also kind of cheapy.
I wouldn't go with the Dell simply because I have a friend who has one (that model), and it doesn't seem worth it for the price. Seeing as how it's your most expensive option. It's a nice machine, definitely. But not necessarily for the price. I have the Dell Studio 14, and I love it to absolute death. But when comparing it to the price of the others, I would recommend against it simply for price. And it doesn't have anything component wise that greatly outshines the others that would compensate for the higher price tag.
Anyway, all that said, I would definitely choose between the Sony and the HP. Realize that you could get a better video card with the HP, and also a better hard drive, which would be a major selling point for me. Product wise...I've not always been happy with HPs. My sister actually has the HP dv6t, and while it's a nice computer overall, the touchpad and the keyboard are the most annoying thing on it. They will drive you absolutely insane. And...you're going to be dealing with those all the time. So that's the only reason I would step away from that one.
Sounds like the Sony is your best bet, as your friends have wisely told you.
But remember, take all of that into account, and be sure the final decision is your own.
As for the Windows 7 64-bit. Yes, you are going to have problems with older games. For the most part, the Windows Compatibility Wizard will be your friend. It will make almost all games playable. But when you get majorly old, like Dark Forces old, you're not going to have any luck. In that case, turn to DosBox. It should be able to play all of those games for you happily. If/when you ever get there, just ask, and I'll be glad to answer any questions you have about it.
Windows 7 is a learning curve over XP, but it's a great operating system. So no worries about that. You'll come to like it.
Anyway, hope that helped at least somewhat, and happy hunting!
Oh, and sorry I took so long to get back to you. I apologize.
"It's not about the legacy you leave, it's about the life you live." ~Mara Jade Skywalker