I think that is a good plan.

Go get a Technet Subscriber Download subscription and you'll have every OS and app they make at your disposal, for testing only of course.

I would spin up an AD domain, install Exchange, SQL 2000/2005/2008, so you can see what is different. Learn how to add users, run SQL queries. I would also not install any patches on your lab box at first, or at least have a copy of your VM's with no patches. This way you can learn about what missing patches can give you a shell. Also install all that software with security not in mind, so you can also see what happens when you do that. For example, install SQL with a blank or easy SA password and see if you can get a shell.

Make sure you setup an AD domain and know how to dump all the password hashes from AD for example. Know how to add users, know what users have the most power, setup logon scripts, know where to look for those logon scripts. You need to be so comfortable  with all this that you don't panic when you're on a pentest. I was in operations for 12 years doing all this stuff and it has paid off immensely in my PT career.

These are just a few examples to get the wheels turning. Bottom line, know what everything does and try to break it.

Cool thank for the advice and this is my plain is to try config it as much to a real work as possible the main problems I have is I never done anything like this before so one don't really know what you would find in real world corp environment and two never attempted to set something like this up before hence the reason for doing it.

I don't know really where to start and I think at the moment this is the hardest thing is starting off with maybe one server and getting that setup. I also plan setting up vp connection to the lab once its done. I recently had a job interview and the company like me but they fill they cant take me on as I am now and wanted to me to try learn more about firewalls, ACL,  VPNS I also plan adding to the lab once its setup so maybe a firewall too.

Great advice so far, and a strong +1 on the Technet subscription. I used that for my MCSE/MCITP studies, and having cheap access to all that enterprise software was a huge benefit.

I'd expand on Hayabusa's #4/note points and tell you to virtualize everything. I believe all those systems are going to be on VMware's ESXi HCL, which is a free bare-metal hypervisor. You can boot that off a 1-2GB thumb drive (I have 2GBs, but I can't remember if that's required) and use all your internal storage for VMs. If you ever need more storage, you can load VMs via NFS instead of purchasing expensive internal storage for those servers.

Even with only 1GB of RAM, you can still get a few light VMs going. XP will easily run with only 64MB and Server 2003 will be fine at 128-256 depending on what you're doing. You'll need more if you add SQL or Exchange, but DCs, web servers, file servers, etc. will be fine with low memory in a lab environment. Many Linux systems will also run very well in the 64-128MB range; just think of all the vulnerable distros you could load

If you get a Technet sub and have access to Server 2008 / 2008 R2, you can also experiment with Hyper-V on the systems that have more RAM (Maybe the 6GB system; 2GB will be pretty lean for that setup). I greatly prefer VMware, but it'd still be good to compare and get acquainted with other technologies.

You'll probably want to add more RAM to those at some point, but you have more than enough to get started with. You could get 20 systems going if you average 512mb RAM per VM.

but where best place to start I am total newbi to this sort things should I start with one server and install server 2003 or is 2008 better ? I want try get server done then use the cisco kit for ccna then build as one.

Just to add to your environment, try to look on vmware.com for virtual appliances.  You can add virtual firewalls and load balancers too to help you learn.  But this may require you to beef up your virtual environments memory.

I dont mind doing some certs but just not sure what best

Just google <os version> system requirements

Start with the minimum and add more as you need it. It's going to vary considerably between a base system and a system with Exchange, SQL Server, etc. Review the requirements for whatever you're planning to install and go from there.