As long as you install the OSes in order with oldest first, you shouldn't have any trouble.

As it is, I've only found a handful of games that don't appear to run on Win 7 (at least I haven't found a way to get them to work) but none of those are sold on GOG anyhow.

Why don't you build a dual-boot machine? But if your version of XP is OEM - your key will be deactivated and you'll end running pirated system :-)

If you don't have a spare PC/laptop with 32bit XP on it and you are still heavy on older (non-GOG) Win9x era PC games (for DOS games it doesn't matter, thanks to DOSBox), I would look into the possibility of making a double-boot system with 32bit WinXP and Win7. That's what I will possibly do if I get a new PC/laptop in the near future (or maybe not, I have a couple of separate XP machines as well, but I prefer keeping all gaming on one system if possible).

Another option might be VMWare (Player) for Win7 and running XP on it, but I haven't tested it myself yet. I was more interested in installing Win98SE on VMWare, and it didn't work out that well (mainly, no support for D3D acceleration whatsoever; my understanding is that this can be achieved for XP as a host OS in VMWare).

That said, the transition to Win7 64bit for games was smoother than I feared. To me it felt a bit like moving from Win98SE to XP, ie. I was pleasantly surprised how well most Win9x games still worked on XP, even if there were some problematic ones (like those which just refused to install on a "NT system").

In Win7 64bit case, it is mainly the older Win9x games with 16bit installers that fail, but there seems to be many workarounds like installing it on a 32bit system (maybe even running in VMWare on the same system???), and then transferring the files to the Win7 system. Also, quite a few Win9x games seem to also have user made Win7 installers, you are not alone wishing to play older games on Win7. But if your old games are mostly from GOG, then this isn't an issue, it is mainly the issue with the original CD-versions of those games.

So I'd say just go ahead with 64bit Win7, and later if you feel its compatibility is not enough for your gaming needs, look into the option of using XP on the side. For double-boot though, I don't know if the only option is to install XP first, and then re-install Win7 on the side?

I have two games that won't work* on my 64-bit Win 7: MDK and No One Lives Forever. Even those probably have ways to make them fuction properly, but I haven't checked. Those are retail copies, so I have no idea if the GOG version of MDK works.

*Which means that 98,8% of my games work.

This is strange bcs my Dad played Sacred 2 on Win7 x 64 so it must work.
The Addon of Sacred 2 does not work bcs the company went bancrupty and barely made a working 32 bit compatible version out of it.

Ooops, wrong discussion, Starflight...

Windows 7 is very compatible as long as the developers haven't screwed up and added some annoying copy protection. In 9 out of 10 cases, it's the copy protection that borks out and causes the game to not install or run.

Starforce is the main culprit here - I still wish I could punch the guys behind it on the nose for causing two of my DVD drives to malfunction not to mention the many other problems including a whole range of my games that no longer work. Seriously, if I had had the time, I'd have taken the scammers op on their offer to fly to Moscow to demonstrate their Starforce breaking my DVD drive ... by smashing my entire PC on their thieving heads.

I think you have that backwards. Vanilla S2 does not work with 7 x64 but the expansion does ;) In rare instances it has worked, but for a good 90-95% of the playerbase using 7 x64 it did not.

I switched from XP to Windows 7 when it came out. It was a sweet deal, I could get it for 35 $. While I was -very- reluctant after the vista fiasco(imo) I must say, that I liked W7 from the start. It made many small GUI changes that sound unimpressive on paper but which are really helpful and save you a lot of hassle.

I don't play old retail games anymore because I have moved to much and stick to GOGs for old games,But with those I haven't encountered a single (W7) problem yet. One game had problems with my new hardware (multicore cpu) but not with windows itself (Hammer & Sickle).

Therefore, as many said before, I can highly recommend the switch. And once you settled in, you wonder how you could live without the new additions.

It's well worth upgrading. I didn't really realise how much XP pissed me off until Win7 came along and made everything so much better.

As for game compatibility, generally it's very good. Your choice of graphics card may prove more decisive in determining which games work and which don't than Windows 7.

What's the worst that can happen. I mean it's Microsoft we're talking about here.

I know this is contradictory to my previous sentence, but you should... rea..ly .... joinnn uussssss!

Virtualbox with Windows XP is the easiest way and safest way to go in my opinion. I was using this program to play classics until I found GOG.

For playing games in a virtualization environment use vmware as it supports directx 9 and you could theoretically run any game.
Windows 7 is a great OS.

At this point I'd argue you've got more to worry about with sticking with XP than from upgrading to 7. Yeah, sure, Vista was a mess. But 7's got it nailed.

Upgrade to Windows 7. DO NOT upgrade to Vista. I've used Virtualbox before but I've never used vmware. I didn't really test any of the older games in Virtualbox because I mostly used it to fool around with Linux distributions.