而且 free 2 user
http://www2.userful.com/products/userful-multiplier

Turn 1 ordinary PC into up to 10 by adding additional monitors, keyboards and mice.
Userful Multiplier is software that lets your Linux computer support up to 10 independent users, monitors and keyboards.
Userful Multiplier (formerly Desktop Multiplier) has been revolutionizing desktop computing since 2002. It's in use on over 20,000 multi-user stations around the world in several industries. It doesn't need any configuration and you'll be ready to go after a simple installation.
Don't run Linux? Then Userful Desktop is the right solution for you. It includes over 40 applications in over 40 languages as well as the operating system.
How Userful Multiplier works

Personal computers sit idle while we read or type. Userful Multiplier takes advantage of this unused computing power, and stations all share resources on the fly. Since computer usage consists of short bursts of CPU activity, each user has access to the full power of the multi-core processor. When more than one user needs the processor at exactly the same time, the computer splits its resources to perform both tasks equally quickly.
Wonder how to set it all up? Learn how to turn 1 computer into 10.
Get into green computing
Userful Multiplier saves money, reduces administration burden, and helps the environment. We’ve saved our customers millions of dollars on hardware costs, millions of hours in installation and maintenance, and tens of thousands of tons of CO2.[/url]
Download Free 2-User edition of Userful Multiplier
The Free 2-User edition of Userful Multiplier (formerly Desktop Multiplier) is a simple and free way to transform your dual-monitor PC into a dual-station PC.
download | install | system requirements | supported distributions | documentation | support
Need extra video cards or keyboards?
Purchase a 4-user starter upgrade kit.
Make money selling Internet access
It's easy to set up a multi-station Internet cafe from one PC. Userful's prepaid cards make it trouble-free & profitable.
Download
Linux Users: Click the package that matches your Linux distribution to begin downloading Userful Multiplier. Installation packages are approximately 14MB each.
RPM Packages (e.g., Red Hat/Fedora, SuSE/SLED, Mandriva, CentOS, etc.) (x86-64)
Ubuntu: You can also install directly from Multiverse (in Ubuntu 6.10, 7.10) or download the Ubuntu Multiverse package http://www3.userful.com/dm/Desktop-Mult ... Ubuntu.zip
Debian Packages (e.g., Ubuntu, Kubuntu, Edubuntu, Linspire, Freespire, Xandros, Debian, Dreamlinus, SimplyMepis, PioneerLinux). Debian x86-64 is coming soon.
Windows/Intel Mac Users: Download the 2-user Live CD to temporarily multiply and share your PC (works on most X86 machines and some Intel Macs).
Install
Install Userful Multiplier following the instructions included in the installation packages. After installation has completed, launch the graphical license tool. The location of the application's menu entry varies depending on your distribution:
(Fedora/Redhat/Ubuntu) Applications -> System Tools -> Userful
(SuSE) Applications -> Utilities -> More Programs -> Userful (System -> More Programs -> Userful)
(NLD) Applications -> Accessories -> More -> Userful
After launching the license tool, click the "activate" button to activate the licensing wizard. The licensing wizard will guide you through the rest of the licensing process.
System Requirements
System requirements
Processor:
Minimum: Pentium III-class (450MHz)
Recommended: Pentium 4 1.7 GHz or better
Memory:
Minimum: 192 MB (plus 64MB for each additional station)
Recommended: 256 MB (plus 128MB for each additional station)
Note: Faster systems will result in better performance for all users. A high-performance hard disk with a large cache (e.g., 8MB to 16MB cache) is recommended.
Free Hard Disk Space: 15 MB
Supported Linux Distributions
RPM Based Distributions:
Fedora 2, 3, 4, 6, 7, 8
SuSE 9.1, 9.3, 10.1, 10.2
SLED 10 SP1
NLD (Novell Linux Desktop) 9
Mandriva (Mandrake) 10.0, 10.1, 2008
Red Hat Enterprise Linux WS 4 & 5
CentOS 4 & 5
Debian Based Distributions: (Be sure to download the Debian packages)
Ubuntu 5.04, 5.10, 6.06, 6.10, 7.04, 7.10
Kubuntu 6.10, 7.04
Edubuntu 6.10
Linspire 5.0
Freespire 1.0.4
Xandros 3.0, 4.0
Debian 3.1 (Sarge)
Dreamlinux 0.5-pre5
SimplyMepis 6.5
PioneerLinux
Documentation
The following documentation is available for Userful Multiplier:
Userful Multiplier Readme) - Describes the Userful Multiplier (formerly Desktop Multiplier) installation and configuration process.
Hardware Quick Start guides:
Setting up a multi-station system (PDF)
Converting a PC into a multi-station system for more than 2 stations (PDF)
Support
Free support for products licensed under this promotion is available through Userful's support forums. Userful offers toll-based phone support for products licensed under a trial or promotional free license.
A license installation help page is also available.