Can I swap out my OS 10.5.8 with my OS 10.4.11?

Hi, all you smart people. I know what you're thinking. Get a real job and upgrade! O.K. but drastic times calls for drastic measures. I purchased a G5 desktop Mac computer with an operating system OS 10.4.11 about 7 or 8 years ago with all the bells and whistles. It's dying on me. I also have a G5 desktop Mac computer with an operating system OS 10.5.8 with no bells or whistles. But it works. I was wondering If I can replace the OS 10.5.8 hard drive with the OS 10.4.11 hard drive or should I just take all these pills at once. Any advice will be greatly appreciated.

The G5 OS10.5.8 is...

ATA

Model Name: Power Mac G5 Quad

Model Identifier: PowerMac11,2

Processor Name: PowerPC G5 (1.1)launch

Processor Speed: 2.5 GHz

Number Of CPUs: 4

L2 Cache (per CPU): 1 MB

Memory: 4 GB

Bus Speed: 1.25 GHz

Boot ROM Version: 5.2.7f1

Serial Number (system): G86191C8R70

Hardware UUID: 00000000-0000-1000-8000-0016CB37FC1D


NVIDIA GeForce 7800 GT:


Chipset Model: GeForce 7800GT

Type: Display

Bus: PCIe

Slot: SLOT-1

PCIe Lane Width: x16

VRAM (Total): 256 MB

Vendor: NVIDIA (0x10de)

Device ID: 0x0092

Revision ID: 0x00a1

ROM Revision: 2152.2

Displays:

Cinema:

Resolution: 1680 x 1050

Depth: 32-Bit Color

Core Image: Hardware Accelerated

Main Display: Yes

Mirror: Off

Online: Yes

Quartz Extreme: Supported

Rotation: Supported

Cinema:

Resolution: 1680 x 1050

Depth: 32-Bit Color

Core Image: Hardware Accelerated

Mirror: Off

Online: Yes

Quartz Extreme: Supported

Rotation: Supported


OS 10.4.11 is...

Machine Name: Power Mac G5 Quad

Machine Model: PowerMac11,2

CPU Type: PowerPC G5 (1.1)

Number Of CPUs: 4

CPU Speed: 2.5 GHz

L2 Cache (per CPU): 1 MB

Memory: 4.5 GB

Bus Speed: 1.25 GHz

Boot ROM Version: 5.2.7f1

Serial Number: G861866QR70

NVIDIA GeForce 6600:

Chipset Model: GeForce 6600

Type: Display

Bus: PCI

Slot: SLOT-1

VRAM (Total): 256 MB

Vendor: nVIDIA (0x10de)

Device ID: 0x0141

Revision ID: 0x00a4

ROM Revision: 2149

Displays:

Cinema:

Display Type: LCD

Resolution: 1280 x 800

Depth: 32-bit Color

Core Image: Supported

Main Display: Yes

Mirror: Off

Online: Yes

Quartz Extreme: Supported

Cinema:

Display Type: LCD

Resolution: 1280 x 800

Depth: 32-bit Color

Core Image: Supported

Mirror: Off

Online: Yes

Quartz Extreme: Supported