Help Troubleshooting: Safari 4.0.2 not working after update

Question

I know that this topic is being discussed on several boards, but I'm not sure what a lot of the advice means. I'm not at all good at troubleshooting on mac.
I restarted my computer yesterday, and the updater listed safari and itunes had updates. I installed both, but got an error when updating safari. Since then when I click on safari the icon bounces once and never opens. The same thing happens with Itunes and Adium. Firefox and Opera both work, but I greatly prefer safari. I've seen a lot of people report that getting rid of plugins works, but I'm not exactly clear on where to find them, because what I've tried doesn't seem to work.
Here's what I've done so far.
Username/library/internet plug-ins ... emptied this folder. No change.
Username/library/itunes/itunes plug-ins ...emptied this folder. No change.
Macintosh HD/library/internet plug-ins ...sill no change.
I'm really afraid to delete any of these things, so when I say emptied the folder, I just moved everything to the desktop. I'm not sure if that's right. Also, I didn't restart the computer after moving the files. could that be it?
I'm not sure what kind of information is most helpful in finding my problem. if there's anything else you need to know, let me know what and I'll get it.

Answer 1

Hm... still no luck.
I restarted the computer as well but it didn't seem to make a difference. Adium and itunes are also still not launching, even after I set the default browser to firefox.
On my desktop is the Safari4.0.2Tiger.dmg
When I click on it, and open the Safari4.0.2.pkg I instantly get an error that says "The Application Installer quit unexpectedly"
If I send a report I get this information
Date/Time: 2009-07-24 14:44:17.315 -0400
OS Version: 10.4.11 (Build 8S2167)
Report Version: 4
Command: Installer
Path: /Applications/Utilities/Installer.app/Contents/MacOS/Installer
Parent: WindowServer [58]
Version: 2.1.9 (104)
Build Version: 37
Project Name: Installer
Source Version: 1040000
PID: 285
Thread: Unknown
Link (dyld) error:
Symbol not found: __ZNK3KJS6JSCell18getTruncatedUInt32ERj
Referenced from: /System/Library/Frameworks/WebKit.framework/Versions/A/Frameworks/WebCore.frame work/Versions/A/WebCore
Expected in: /System/Library/Frameworks/JavaScriptCore.framework/Versions/A/JavaScriptCore
/System/Library/Frameworks/WebKit.framework/WebKit
Model: MacBookPro1,1, BootROM MBP11.0055.B08, 2 processors, Intel Core Duo, 2 GHz, 1 GB
Graphics: ATI Radeon X1600, ATY,RadeonX1600, PCIe, 128 MB
Memory Module: BANK 0/DIMM0, 512 MB, DDR2 SDRAM, 667 MHz
Memory Module: BANK 1/DIMM1, 512 MB, DDR2 SDRAM, 667 MHz
AirPort: spairportwireless_card_type_airportextreme (0x168C, 0x86), 1.4.4
Bluetooth: Version 1.9.5f4, 2 service, 0 devices, 1 incoming serial ports
Network Service: AirPort, AirPort, en1
Serial ATA Device: FUJITSU MHV2080BH, 74.53 GB
Parallel ATA Device: MATSHITADVD-R UJ-857
SCSI Device: SCSI Target Device @ 0
USB Device: Built-in iSight, Micron, Up to 480 Mb/sec, 500 mA
USB Device: Apple Internal Keyboard / Trackpad, Apple Computer, Up to 12 Mb/sec, 500 mA
USB Device: IR Receiver, Apple Computer, Inc., Up to 12 Mb/sec, 500 mA
USB Device: Bluetooth USB Host Controller, Apple, Inc., Up to 12 Mb/sec, 500 mA
I have no idea what that means.