Xbox

If you want like 200 hours of game time get Oblivion for X Box. Also Fallout 3 is awesome but I wouldn't play it at the same time as Oblivion, because they use the same engine and you might get a little bored of it. Both also have multiple expansions.

The 360 has a ton of everything you're looking for actually.  While I support the PS3 like it's my job (oh wait...) I can definitely point you in the right direction for games for the 360.

Blue Dragon and Lost Odyssey play like traditional turn based RPGs and offer a ton of game time, so if you've got a lot of time to burn, definitely look into these two.  Oblivion and Fall Out 3 are definitely great games that take place from a first person view and also has RPG elements.  I'm a huge fan of Fall Out 3 actually so if you like FPS games and RPGs definitely look into getting it.  Since you're looking into RPGs and shooters, also take a look at Mass Effect.  It combines RPG elements with a third person shooter.  Dragon Age: Origins plays a lot like Baldur's Gate and is a a lot of fun to play and has a ton of replay ability.  Also keep in mind that Final Fantasy XIII is coming out in a few months, so you have that to look forward to.

As for shooters, the most obvious answer is Call of Duty: Modern Warfare 1 & 2.  Both have amazing single player campaigns and fantastic online multiplayer.  Another game that I want everyone to play is Bioshock.  It's my hands down favorite first person shooter by a long shot and the second one is coming out in under a month.  There's also Halo 3, Halo: ODST, Gear of War and Gears of War 2 out which are all reasonably cheap now and are still amazing games.

As for real time strategy, there really isn't a lot.  The only ones that I can really think of are Halo Wars, Command and Conquer: Red Alert and Command and Conquer: Tiberium Wars.  I'm not much of an RTS player, so I don't know how they are.

I hope this helps you out.

Any of the Lego adventures games are a lot of fun (Batman, Indiana Jones and the Star wars series). For first person shooters I am a big fan of Left for Dead 1 or 2, its about killing zombies.

LEGO games FTW! there is something so satisfying about playnig as a LEGO chewbacca and ripping the LEGO arms off of LEGO storm troopers *contented sigh*

most rpgs i can tell you about from experience have already been mentioned, but just bc i love it so much ill mention that elder scrolls 4: oblivion is awesome, and elder scrolls 3: morrowind is worth playing... also i heard borderlands was a pretty good fpsrpg

ahaha oh wow thanks guys/ gals!

Ok so far I have Mass Effect 1, Assassins Creed 1 & 2, Red Faction and Gears of War lol I think that should fill my boots. I've already played Fallout 1-3 on my computer so I felt little need for them on the system.

I'm just worried Im going to purchase a mainly online game by accident thats all.