I'm not really bothered about 'merging' accounts as such, but I'm wondering if the game will install and run okay with my new account. I am not really bothered about retrieving my old character and if the account it was tied to went inactive, I'm not bothered.

I think it won't work. The key should be one-time use, same as on Steam. So if you want access to Prophecies campaign, you have to find your login and password to the old account, contact the support as captfitz said or buy the Prophecies campaign again.

As far as I know, GW Accounts never go inactive (unless you're banned I guess). If you can prove that you're the owner of said account, they should be able to give it back to you in some way.
About installing Prophecies : there's only 1 GW Client, and it downloads whatever it needs from Anet's servers. You don't need to "install" Prophecies to access the Prophecies content. All you need is a Prophecies access key linked to your current account.

guild wars trilogy is on sale for $40 on steam right now
buy buy buy! that's a stupid good deal.

I will return to Age of Conan I think because of this deal. I sold my boxed copy long time ago. :)

I bought the GW Trilogy from GoGamer.com a while back. I found it to be kind of boring. I was playing a healer/benevolent leader and was attempting to let my henchmen do the fighting for me.
Maybe I need to start again and try a more physical class.

Well I've also ordered Factions:Collectors edition from Sendit.com for a rather cheap price.
I've got the repackaged "White cover" Nightfall, and the package mentions a bonus Fire Imp, where and how do you get this?

While in town or outpost, just type /bonus and you will get all bonus items you can have. But beware that the fire imp summoning stone works only for lvl 1-19 characters, at lvl 20 you won't be able to use it.

OK, I'm up for it. Just rolled a new character (Paragon, name is Astrape Winterstorm... don't ask). Add me. But first I have to finish a small quest to get that minipet from the PC Gamer special issue.

Okay, NCSoft were very helpful, they eliminated my old account from Prophecies, they said it was the only way but gave a reissued serial key to tie it to my account with Nightfall. So I have Nightfall and Prophecies and have Factions on the way.
My Prophecies character is named "Prince Veyne", but since it's tied to my account the friends list appears on both campaigns with the same names.

Ah guys, I was meant to get an invite to the Guild, I've got Prophecies, (character name Prince Veyne), Factions (Mikal R Kayn), and Nightfall (Skarr Yeoman)

Now that I finally got myself a copy of GW Trilogy delivered all the way down here to Brazil, it seems everyone gave up playing!
Everyone can add me, Bizarre Liadon. If the guild is active and you're recruiting criminals and bums, PM me!

oh I've been playing :D

I'll add you, I'd also like to be in the Guild, I've had too Prophecies guild offers that I've turned down due to waiting for the GOG one. Question though, does a guild invite only apply to the character in one campaign, or does it apply to multiple characters that the account has. I've got three characters, one for Prophecies, one for Nightfall and one for Factions.

It does apply for all your characters.