Sorry, if all settings are at their lowest possible there is nothing to be done. With your bad video card (Mobile Intel 945) you are lucky to get 30-40 FPS.
OK, the chipset and Ethernet drivers installed successfully. The graphics driver link was broken; I've fixed it above, please try installing it. Provide another MTADiag log after installing.
Then the Ethernet driver is not responsible for any packet loss, your wireless connection is.
Are all graphics settings at their lowest? Does GTA:SA single player perform okay?
Please install the following:
Graphics driver
Audio driver
Ethernet driver (do a Repair install if prompted)
Chipset drivers
Provide another MTADiag log after installing.
Please download and run MTADiag and follow the instructions. It will automatically detect and remove any incorrect compatibility mode settings for you. Also post the MTADiag log it generates so I can see why you require Win98 compatibility mode.