[TYPO3-english] need some suggestions, typo3 4.5 or 6.2 ?

[Chai name]

hello all, 


I'm quite new in Typo3.

first, let me describe our problem in developing Typo3 website.

our customer has a STRICT conditions 

the server environment :
 - OS: Windows Server 2008 R2 64bit
 - DB: Microsoft SQL Server 2005
 - PHP: version 5.2.12
 - web server : IIS7.5

Customer want to use Typo3 v6.2 but it's required PHP5.3.7+

as for example, PHP5.2 is not supporting the namespace 

 - Should we go back to use Typo3 4.5  which is outdated ?

 - if we really have to use Typo3 4.5 how about the security risks or any best practices or TO DO when we have to work on it?

we really need the customer to update their own server specification to meet the Typo3 6.2 spec

but it's quite sure, the customer will not upgrade their server environment.

also please suggest me about MS SQL Server
as I'm not sure is MS SQL Server 2005 working properly with Typo3 ( any version )?



if you want another details, please ask I will give your more details

Thanks in advanced