64-bit all the way. Yeah, I still use a few 32-bit oldies which have no x64 counterparts. jBridge takes excellent care of bridging those. Cubase's VSTBridge is no match for that, you really are rolling the dice if you use it, especially with anything older than VST 2.4 standard.
Desktop: i7 3770k, 32 GB RAM, nVidia GTX770 + GT640-DCSL fanless, 3 monitors (30" 2560x1600 + 2x 27" 1920x1080), 256 GB SSD (OS), 2 TB SATA III (audio), 3 TB SATA III (sample libraries), 3x 3 TB USB 3.0 (backup/archives), RME UFX, Win 8.1 Pro x64, Cubase 7.5, Sonar X3, Vienna Ensemble Pro 5.
Slaves: 2x i7 2700k, 16 GB RAM, 256 GB SSD, 3 TB SATA III, Win 8.1 Pro x64, Vienna Ensemble Pro 5.
Laptop: 17" HP EliteBook 8770w (i7 3820QM 2.7 Ghz/3.7 Ghz max OC, 16 GB RAM, 256 GB SSD, 1 TB SATA III), RME Babyface, Win 7 Pro x64, Vienna Ensemble Pro 5, Cubase 7.5, Sonar X3.