Your system should run it at full speed, even with the 30 FPS patch. My system do it and yours is not so much different in power. I'm using the 30 FPS patch. I almost always have 30-31 FPS, no audio problems (only with the audio fix, normal builds + svn are bad in audio), just in some rare cases with many enemies etc., it can drop to max. ~20 FPS, but not less.
I'm using the 3.0-496 build with audio fix. My config is like that:
1.) Config
General
Enable Dual Core: on
Enable Idle Skipping: on
Framlimit: Audio
CPU Emulator Engine: JIT Recompiler
Remaining "General": off
Audio
DSP Emulator Engine: DSP HLE emulation
Volume : 100%
Enable DTK Music: on
Audio Backend: DSound
Sample Rate: 48 KHz
Remaining "Audio": off
Wii
Use EuRGB60 Mode: on
Aspect Ratio: 4/3
Remaining "Wii": off
2.) Graphics
General
Backend: Direct3D
Fullscreen Resolution: same as desktop (1600x1200)
Aspect Ratio: Auto (4/3 for me)
V-Sync: off
Use Fullscreen: on
Remaining "General": off
Enhancements
Internal Resolution: Auto (looks like 4x Native, no difference at all)
Anti-Aliasing: 4x SSAA
Anisotropic Filtering: 8x
Scaled EFB Copy: on
Force Texture Filtering: on
Per-Pixel Lightning: off
3D Vision: off
Hacks
Skip EFB Access from CPU: off
Ignore Format Changes: on
EFB Copies: Texture! (if you use "Ram" you will loose many FPS)
Texture Cache: Safe (can't see any difference with "Fast" anyway, equal what I use I get full FPS)
External Frame Buffer: Disable
Fast Mipmaps: on
Disable Per-Pixel Depth: on
OpenMP Texture Decoder: on
Remaining "Hacks/Other": off
Advanced
Dump Textures: on (for me, because I'm trying to dump all existing textures, eg. with "EFB Copies: Ram" it would generate thousands of duplicated textures)
Remaining "Advanced": off
Try those configurations, maybe you're lucky.