I was looking at what hardware and software requirements Microsoft had to say for FAST Search Server 2010 for SharePoint.

There are a few things to note:
RAM:
Minimum – 4GB RAM
Recommended – 16GB RAM

CPU:
Minimum – 4 CPU cores, 2.0GHz CPU
Recommended - 8 CPU cores, 2.0GHz CPU

Hard Disk:
Minimum – 50GB disk
Recommended – 1TB disk

Operating System:
1. Windows Server 2008 SP2 x64. All regular Standard/Enterprise/Datacenter versions are supported.
2. Windows Server 2008 R2 x64

Some additional points:

1. The server must be fully updated with the Service Pack and updates and restarted before you install FAST Search Server 2010 for SharePoint.
2. Do not install FAST Search Server 2010 for SharePoint on a server that runs a Domain Controller.
3. Use the server for FAST Search Server 2010 for SharePoint only. Do not install FAST Search Server 2010 for SharePoint on the same server as SharePoint Server 2010.
4. Make sure that the FAST Search Server 2010 for SharePoint server name is not more than 15 characters long.
5. .NET Framework version 4 is not supported. Only .NET Framework version 3.5 SP1.
6. Ensure that the user who runs the installer is a member of the Administrators group.
7. Do not run FAST Search Server 2010 for SharePoint as a local administrator or a domain administrator.
8. Plan to install Windows updates after a controlled shutdown of FAST Search Server 2010 for SharePoint.
9. Exclude the FASTSearch folder from anti-virus scanning to prevent the anti-virus software from falsely identifying FAST Search Server 2010 for SharePoint data files as malware.
10. If you are using a proxy server and wanting to use FAST across multiple SharePoint farms, there are additional steps you need to perform.
11. If your anti-virus software allows it, it is recommend that you exclude the following FAST Search Server 2010 for SharePoint processes from scanning:

• cobra.exe
• contentdistributor.exe
• create_attribute_files.exe
• docexport.exe
• FASTSearch.exe
• FASTSearchExec.exe
• fdispatch.exe
• fdmworker.exe
• fixmlindex.exe
• fsearch.exe
• fsearchctrl.exe
• ifilter2html.exe
• indexer.exe
• indexingdispatcher.exe
• jsort2.exe
• make_pu_diff.exe
• MonitoringService.exe
• pdftotext.exe
• procserver.exe
• qrserver.exe
• spelltuner.exe
• truncate_anchorinfo.exe
• walinkstorerreceiver.exe
• walookupdb.exe
• webanalyzer.exe

Read more here: http://technet.microsoft.com/en-us/library/ff381239.aspx

This is a GREAT document if you want to look at capacity planning for FAST Search Server 2010.
If you have a multi-server SharePoint 2010 farm running on the Enterprise license with a dedicated Search Server, then your FAST Search Server 2010 would be of no extra licensing cost to you.
(Enterprise license is per server. Each FAST Search Server 2010 for SharePoint 2010 consumes one enterprise server license.  Disclaimer: please consult a Microsoft licensing specialist ).

When you read this document, you will understand how to:

• Define performance and capacity targets for your environment
• Plan the hardware required to support the number and type of users, and the features you intend to deploy
• Design your physical and logical topology for optimum reliability and efficiency
• Test, validate and scale your environment to achieve performance and capacity targets
• Monitor your environment for key indicators

I enjoyed this and I thought I would share this with you..

http://www.microsoft.com/downloads/en/details.aspx?FamilyID=65b799e3-825c-4398-8cd7-3311d3297997&displaylang=en