You can download VMWare from http://downloads.vmware.com/. I'm using VMWare WorkStation 7.0.1 build-227600 although I believe VMWare Player also allows you to not only play VMs but also create them too now.
While setting up your VMWare workstation, use something along these lines:
Choose Advanced
Virtual Machine Name: SharePoint 2010
Location: C:\WEBTECHY\VMs
Number of processors: 1
Number of cores per processor: 1
Total processor cores: 1
Memory: 4096 GB
Network connection: Use network address translation (NAT)
I/O adaptor types: LSI Logic SAS
Disk: Create a new disk
Virtual disk type: SCSI
Maximum disk size: 80GB
Store virtual disk as a single file
Disk File: C:\WEBTECHY\VMs\SharePoint 2010.vmdk (make sure location is right)
I then received the following ("You have configured this machine to use a 64-bit guest operating system"):

NB I have a Dell XPS 720, and I first had to reboot the host machine and go into BIOS and enabled Virtualization (VMM can utilize additional capabilities).
I used Windows Server 2008 R2.

You may want to change the computer name to something more memorable at this point.
You then need to download SharePoint 2010 Beta from:
http://sharepoint2010.microsoft.com/try-it/Pages/Trial.aspx
NB I selected for Internet sites as I wanted the full capabilities although I think the download is the same just a different key.
Start the install.

Now select "Install software prerequisites"
# Application Server Role, Web Server (IIS) Role: configured successfully
# Microsoft SQL Server 2008 Native Client: installed successfully
# Microsoft "Geneva" Framework Runtime: installed successfully
# Microsoft Sync Framework Runtime v1.0 (x64): installed successfully
# Microsoft Chart Controls for Microsoft .NET Framework 3.5: installed successfully
# Microsoft Filter Pack 2.0: installed successfully
# Microsoft SQL Server 2008 Analysis Services ADOMD.NET: installed successfully
If they don't install, then install them one by one by downloading from MS.
Then go to Windows Update and install the required updates.

Restart your machine.
A lot of posts have mentioned installing KB971831 (called Windows6.1-KB976462-v2-x64.msu) from MS. However, on my first attempt it said that the update did not apply to my machine. This is available from:
http://support.microsoft.com/kb/971831
However, I think the update you actually need is from here:
http://connect.microsoft.com/VisualStudio/Downloads/DownloadDetails.aspx?DownloadID=23806
Its name: Windows6.1-KB976462-x64
NB the link to the direct download would also not work, I had to use the MS FTM (link to download on that page).
You could also try: http://support.microsoft.com/hotfix/KBHotfix.aspx?kbnum=976462&kbln=en-us
Restart your machine.
NB I tried to install without this patch initially, but it failed. I therefore re-ran the SharePoint Products Configuration wizard below (which was added to the start menu). The error was:
Failed to create sample data.
An exception of type Microsoft.Office.Server.UserProfiles.UserProfileException was thrown. Additional exception information: Unrecognized attribute 'allowInsecureTransport'. Note that attribute names are case-sensitive. (C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\WebClients\Profile\client.config line 56)
Now run the install again, and you'll be prompted for an install key:

Which you can get from here:
http://technet.microsoft.com/en-us/evalcenter/ee391660.aspx
Installation of the SharePoint Server 2010 Beta requires one of the following product keys:
SharePoint Server 2010 Beta (Enterprise CAL features): PKXTJ-DCM9D-6MM3V-G86P8-MJ8CY
SharePoint Server 2010 for Internet Sites Beta, Enterprise: PKXTJ-DCM9D-6MM3V-G86P8-MJ8CY
Now we need to choose the type of install.

Choose Standalone.




That's SharePoint installed! :-) At this point you'll probably want to setup a SharePoint 2010 site. The page below will load up (add it to your trusted sites and reload to remove error in bottom left):

Use default groups (you can always amend):

You should now see the homepage.

For development, you'll also probably want to install:
Download and install Visual Studio 2010
http://www.microsoft.com/visualstudio/en-us/download
Download and install SharePoint Designer 2010 Beta (64-bit)
http://www.microsoft.com/downloads/en/confirmation.aspx?familyId=eeda9ab1-ac53-4870-9e1c-38940343d677&displayLang=en#
References:
Difference between IA64 and x64
http://mikedimmick.blogspot.com/2006/03/whats-difference-between-x64-and-ia-64.html
