I browse porn all the time on Windows and Linux, all you need to do is be smart (use NoScript in Firefox and only allow the scripts you need). You're pretty safe sticking to the major sites that are plays on the name "Youtube". If you're really worried, keep a bootable USB key that won't mount your hard drive and surf porn that way. There's some private torrent trackers for really high quality stuff, don't know if they're still active, but something should be if you want HD stuff.

Abandonware is always gonna be a "do you trust the uploader" kind of thing. Most exploits will be bigger than old NES ROMs, but not even all of them. If you're using more recent stuff... I'd say scan it and rely on fellow user reviews. Find a private BT tracker for people who share that shit, dunno, I'm too busy to follow that scene.
I do, XP is genuinely a pain in the ass compared to Win 7, it's hard to believe until you get to used to Win 7, you'll literally grit your teeth every time you get stuck using XP thereafter.

Actually, I've been using Win7 for about 2 years. My most recent rig is a Win7 64 bit install and it's networked with my old XP rig. I use both on a daily basis (each rig has a separate screen, but I'm using Synergy to allow me to control both rigs with the same KB and mouse). I've found some things that are a bit PITA in XP compared to Win7, but nothing too major. I'm not what would be considered a major power user though, so that may make a difference.

*edit* Attached is a pic of my setup. Rig on the left is the Win7 rig and the right hand one is the XP rig. Ignore the rat's nest of wires. They've since been cleaned up. Sort of.

Holy shit, do you just roll a sleeping bag under there so you don't have to turn on the heat in the winter?

LOL. Indeed, it's quite cozy in the winter. Summer days are a bit uncomfortable by times though...

Don't reinstall often. I typically just buy another HDD and put a new OS on it. Saves me hours of bullshit and I retain all of my data.

You see this is why tabular browsing is such a terrible idea.

Ever since I got off the Win 9x series of OSes I've never had to reinstall except due to hardware failures or moving. Even moving between systems I managed to have the same install of Windows 2000 boot up on a couple different motherboards before the hard drive it was on finally died. My latest reinstall was a couple months ago, but that was from switching my stuff around to have an SSD as my OS drive.

If you are concerned, you can always use a virtual machine to browse for stuff and never move any files between it and your main OS.

Legitimate porn is usually deemed more ethically acceptable but that is pretty much the most abundant source of the worst malware.

A lot of the abandonware that is relatively easy to find are the cracks that were done by developers themselves, disguised as pirate organizations, as means of promoting their game in a way that not everyone in the world felt entitled to download.

Larger sites that offer good quality abandonware are, more or less, mousetraps trying to catch larger menaces.

It's a matter of using your own morale common sense and avoiding higher profile and current items.

Pretty much anything I've snagged has been long since discontinued and unobtainable by any other means.

I completely reformat every 6 months or so. Feels good to clean the cobwebs out, and you should be keeping regular backups anyway so restoring stuff is no big deal.

I don't really set a time-frame on formatting as such but I probably average around 8-12 months before doing it.

I keep all none program data on a separate drive so it's a pretty painless operation anyway.

That's actually a good idea but how much are hard drives in the UK?

The last time I checked (around two years ago) online adverts were actually the biggest sources of malware, primarily Flash ads... followed by poisoned PDFs... yeah thanks Adobe!

On average, i would say, about every 18 months. I always try to back-up any gems that i find on the internetz.

You do know that there are also live Win7 cds out there, right? Not sure which option is better, but tell me if you want a link to them.

Well, I usually nuke my main Windows installation when I have too much issues with it. Take the current situation, for instance: I'm on Vista 32-bit right now, but the GPU isn't working as it should (some fucked-up driver settings with a lower ForceWare "profile" forced at the start, it's essentially working with a lower voltage at half its performance capabilities), VLC won't use GPU acceleration correctly and I can't apparently install DirectX 11.

I've tried a newer HDD with Windows 7 (32-bit, too) installed on it: all of the aforementioned issues have disappeared. So, in the end, I will take my time (I need a couple of weeks, at least, to complete the operation) to destroy Vista and permanently install Windows 7 64-bit asap....

Oh, as for data loss: I try to backup my partition and my data as much as I can....