You can run VMware Vsphere 4.0 in VMware Workstation, i am providing the steps how to do that below.
1.Before Starting VMware Vsphere 4.0 in VMware Workstation 7 your Desktop or Laptop must meet the hardware requirement.
2.Your Desktop or Laptop should be 64 bit and VT must be enabled in the BIOS and should have good amount of memory.
3.Go the the BIOS of your system and enable VT or Virtualization.
4.Ok, now You can download a trial version of VMware Workstation 7 and VMware Vsphere 4.0 from VMware site.
5.Now, Run the VMware Workstation 7 in your system, its default installation go with next, next , next.. finish.
6.Once the VMware Workstation Installed,open it from Start Menu or from Desktop icon.
7.There you can create a new VM, in OS option select VMware Kernel 64 bit, and give the required HardDisk Space and importantly assign Memory minimum of 2 GB.
8.Now, Go to the settings of just created VM in CD place show the path ISO file which you have downloaded from VMware Site and above to that select CD connected when VM power on.
9.Click OK, Now go to the file where you have created that ESX VM, and select the .VMX file right click on it and open it with notepad.
10.Once you have Opened .VMX file with notepad go to the bottom of that file and add these line.
"monitor_control.backdoor_restrict=true"add above given line without any inverted comma's
10.Now, start the VM,once you start the VM you will find VM will start booting up and soon you will find the VMware Vsphere 4.0 Installation menu.
11.As you are installing it for test environment, you can go ahead with default installation, but for production installation you must follow with the VMware Vsphere 4.0 installation guide.12.In the installation process give the time zone,and root password whereever it ask and give one Static IP, ip should be in such a way that it should communicate with your physical BOX.
13.After installation finises, VM will reboot.
14.Now, you can find the VM Vsphere started completed onthe main screen you can find the url or ip which you have given it for installation.
15.Go to the browser of your physical system enter the ip which you have given in vm vsphere 4.0 installation and click on enter.
16.For first time when you open that ip you will get with SSL certificate message, add that SSL certificate.
17.Now , you will get the screen with the VMware Vsphere login page, there you will also get link to download Vsphere Client Download, just click on it and download it.
18.After Downloading Vsphere Client, install it on your physical machine.
19.Now open that client and give the IP of the vmware vsphere 4.0 which you have given and in username place give root and password of that.
20.Once you click on login you will again get the ssl message, select ignore and install.
21.Now the next screen will appear with your Vsphere 4.0 infrastructure.
22.Now in that you can create the VM also.
That'st it this way you can install VMware Vsphere 4.0 in your VMware Workstation 7.if you need any help or got any error while installating it you can post comments to me.
All The Best!!!!!!!!!!!