» Network adapters: Especially on notebook computers, there is often more than one network device. Disabling the network devices that you do not use will definitely save you some booting time.
» FireWire: If you have 1394 connections, otherwise known as FireWire, you might consider disabling them. Unless you are using your FireWire port to connect your digital video recorder to your computer, or have other external FireWire device, you have no need to have this device enabled.
» Biometrics: Some of the latest computer hardware includes biometric sensor equipment such as a fingerprint scanner. If you do not use these security features, you can save time by disabling theses devices, too.
» Modems: Do you have a broadband connection? If so, consider disabling your modem. If you rarely use it, why not disable it? If you ever need to use it again, just re-enable it.
» TPM security chips: Does your computer have a Trusted Platform Module (TPM)? These chips are typically used as a secure place to store an encryption key that would be used for something such as hard drive encryption. If you are not using any of these advanced security features of Windows 7, disable these devices, too.
» Multimedia devices: Your computer has lots of multimedia devices. Take a look at the “Sound, video, and game controllers” section in Device Manager. You will find a lot of device drivers that are loaded during your boot. Some are used by all users, but you will find a few that you do not use. For example, I do not use my game port or my MIDI device, so I disabled both of them.
» PCMCIA cards: If you are a laptop user, consider disabling your PCMCIA card controller located under “PCMCIA adapters.” The PCMCIA (Personal Computer Memory Card International Association) slot is a special expansion slot that is rarely used today on laptops except for wireless and wired network cards and card reader attachments for compact flash and other solid-state memory cards. Most laptops now have builtin network adapters, and some even have built-in wireless adapters. If you do not use your PCMCIA adapter, it is yet another device you can safely disable.
Do not disable any hardware devices located under the Disk Drives, Computer, Display Adapters, IDE Disk Controllers, and the System sections (except for the system speaker). These hardware devices are critical to the operation of your system.
Source of Information : Windows 7 Tweaks 2010