1. Zelda: A Link to the Past

2. Pirates! (for the NES, the new one for PC is excellent as well)

3. Guitar Hero II

4. Counter-Strike: Source

5. Mechwarrior2 / Mechwarrior 4

6. GranTourismo 3/4

7. Rome/Medieval II: Total War

8. Rise of Nations/ Civ IV (different, but basically the same)

9. Mortal Kombat II

10.God of War

11Oblivion

Others: Sim City for SNES, Super Mario World, Resident Evil 4, Duke Nuke'em 3d, Silent Hunter/Silent Service, Gettysburg/Antietam, Descent/X-wing vs. tie fighter

Personally, I enjoy Mech 4: Mercs very much. If you don't have all of the Mech 4s, there's a pack sold at Eb/bb/Wherever that has Mercs, Vengeance and the black knight expansion.

It is too bad a new Mechwarraior hasn't been released lately. Still probably my favorite series of all time.

DuckHunt was awesome.  This thread kind of makes me want to go to my grandparent's house and play the old NES.

I have Halo on the PC.  I thought it was fun.  The vehicles were well done I thought.  The multiplayer was OK at best.

I, honestly, haven't really loved a single player shooter since Duke Nuke'em. Halo and HL/HL2 were fun for a while, but they just didn't keep my attention for that long. 

I love CounterStrike: Source.  I've wasted way too much of my life playing that.  Joined clan, played cal, etc.  I don't know why that is so much more fun, to me, than single player FPSs.

Back in the day I bought 8 megs of ram so I could have the 16 required to play Mechwarrior 2 Mercs.

Since then, Oblivion.  Went from a 6600gt to an X1800XT. Expensive game, that (300 + 50). Glad I did though.  Haven't run into a game yet that the x1800xt can't handle.  Glad I didn't spend the extra hundered for the x1900xt, as the x1800xt, when OCd, usually outperforms the x1900xt by a fair margin (at least in the games I play).

You know everything you buy automatically becomes your wife's when you get married...so...you're kinda screwed.Ryo_Kensen

This is true, and there's not a whole lot you can do about it.  My wife likes the game as well and I'm glad she is enjoying herself.

 The only thing to do, really, is encourage her for as long as you're not bored, and then go play some CounterStrike: Source.

Pirates! is a lot of fun.  Port Royale if you want something a little more in depth, but not as fun.

Rome/Medieval total war  are also great games. Civ IV is also fun.

As for single player FPSs, they're pretty much all the same in my book. I'd say HL/HL2 if you've never played them.

For a decent gaming/multimedia PC, its generally better to build.  It really is quite simple to put everything together.  The hard (and fun) part is picking out the parts. 

 The only time I'd recomend buying a system is either on the low end, or if you have absolutely no parts you can recycle and don't care about your monitor very much.  You can get a good amount of computer that comes with a crappy monitor for a couple hundred bucks form any electronics store.  Not a bad deal, but you're getting mistery parts with virtually no upgrade potential (GPU maybe).  Same with midrange comps if you would need OS, mouse, keyboard, monitor.  If you have those things, you're better off building. You can pick quality parts that OC well and you'll probably still save $