You really should check out Aspyr's Mac Games section.
Just one game converter's selection:
007? Nightfire? - Mac
4X4 Evolution 2 - Mac
Star Wars® Jedi Knight® II: Jedi Outcast? - Mac
Star Wars® Jedi Knight®: Jedi Academy? - Mac
Star Wars®: Galactic Battlegrounds? - Mac
Star Wars®: Knights of the Old Republic® - Mac
American McGee's Alice? - Mac
Battlefield 1942? Deluxe Edition - Mac
BloodRayne? - Mac
Call of Duty? - Mac
Clive Barker's Undying? - Mac
Command & Conquer? Generals - Mac
Cro-Mag Rally - Mac
Delta Force®:Black Hawk Down® - Mac
Escape from Monkey Island? - Mac
Extreme Fun Compilation - Mac
Harry Potter? and the Chamber of Secrets? - Mac
Harry Potter? and the Sorcerer's Stone? - Mac
Homeworld®2 - Mac
IPuppet Presents: Colin's Classic Cards - Mac
Indiana Jones® and the Emperor's Tomb? - Mac
Kelly Slater's Pro Surfer® - Mac
Kelly Slater's Pro Surfer® - PC
Lara Croft Tomb Raider?: The Angel of Darkness? - Mac
Law & Order?: Dead On The Money - Mac
Leave the Lights On Compilation - Mac
Medal of Honor Allied Assault? Breakthrough - Mac
Medal of Honor Allied Assault? Deluxe Edition - Mac
Medal of Honor Allied Assault?Spearhead Expansion Pack - Mac
Medal of Honor: Allied Assault? - Mac
NASCAR® Racing 2002 Season - Mac
NASCAR® Racing 2003 Season - Mac
Otto Matic? - Mac
Return to Castle Wolfenstein? - Mac
Sid Meier's Alien Crossfire? - Mac
SimCity? 4 - Mac
SimCity? 4 Rush Hour - Mac
Space Colony? - Mac
Spider-Man? - Mac
SpyHunter® - Mac
SpyHunter® - PC
Star Trek?: Voyager ® Elite Force? Expansion Pack Combo - Mac
Star Trek?: Voyager® Elite Force? II - Mac
The Lord of the Rings?; The Return of the King? - Mac
The Sims? - Mac
The Sims? Hot Date - Mac
The Sims? House Party - Mac
The Sims? Livin' Large Combo - Mac
The Sims? Makin' Magic - Mac
The Sims? Superstar - Mac
The Sims? Unleashed - Mac
The Sims? Vacation - Mac
Tiger Woods PGA® Tour 2003 - Mac
Tom Clancy's Ghost Recon?: Desert Siege? - Mac
Tom Clancy's Rainbow Six® 3: Raven Shield® - Mac
Tom Clancy's Splinter Cell® - Mac
Tomb Raider® Chronicles - Mac
Tomb Raider®: The Last Revelation - Mac
Tony Hawk's Pro Skater? 2 - Mac
Tony Hawk's Pro Skater?3 - Mac
Tony Hawk's Pro Skater® 4 - Mac
Tony Hawk's Pro Skater® 4 - PC
Wakeboarding Unleashed? Featuring Shaun Murray - Mac
Wakeboarding Unleashed? Featuring Shaun Murray - PC
X2 Wolverine's? Revenge - Mac
Zoo Tycoon? - Mac
Zoo Tycoon?: Marine Mania? Expansion Pack - Mac
Notice Battlefield 1942 and Jedi Academy?
Halo is also out for Mac, and Halo 2 is coming. I think Battlefield Vietnam is also coming. I *hope* Star Wars: Battlefront will be on the Mac as well.
This is just from *one* of the Mac game creators/converters.
There are plenty of games out there.
Besides, it never hurts to keep a spare Windows PC with a graphics card around for the Windows-only games like SFC3...
Anyway I don't intend to upgrade to Longhorn for a loong time. Maybe someday I'll get Longhorn, but only went I can get a 5 GHz PC for around $500 (since Longhorn's minimum recommended will be 4 GHz) with a good graphics card, and only if future games require a computer that powerful and require Longhorn. If I can get by without having to waste my money on Longhorn (note that each version of Windows is more expensive than the last: 3.1 was $50, 98 was $100, 2000 Pro was $200, and XP Pro is $300...what'll Longhorn be?
I'll stick to my Mac for now, where my processor isn't bogged down by such a bloated operating system. This 2.6 GHz P4 will probably be my last PC desktop for a while (at least for me, there is one member in my family who likes Windows, everyone else likes Mac). My next desktop will be my first Mac desktop (i've only owned laptops so far).