Hey FedoraRefugee, you are ahead of me, I was going to say about the same thing on Fedora, CentOS and Scientific...
Yes Fedora is NOT a free Red Hat but as you said rather "Fedora is used as a test bed to develop future components of RHEL".
CentOS is really Red Hat less branding, logo etc... Scientific is very near of Red Hat too but maybe less exactly and it has some softwares (e.g. scientific softwares, of course, like its name) not in RHEL, and about the NTFS volumes (they are popular for external drives), SL (self-)mount them like a charm...
Also, SL (Scientific Linux) excels in the LiveCDs. There is an interesting aspect about SL Live DVD: you can connect you as root or as (sl)user, and you can choose your password (without being worried by its size, passwords as I like them on unconnected "net"books can work….) every time you boot. This might give good habits to people unacustommed to them…
About the desktop, yes you can use a RHEL clone for your desktop, I do that, but no real multimedia "things" in the official repos (no mp3 support or several other multimedia formats - codecs, for example gstreamer plugins - and multimedia players like xine or mplayer) Of course there are some other repos where you'll find them, the only problem is you must have a great attention about compatibility between the repos, if not you'll go in the famous rpm hell.
About older apps:
CentOS is an Enterprise-class operating system and as such is more about stability and long-term support than cutting edge. Major package versions are retained throughout the life cycle of the product. This is generally what Enterprise wants and affords developers a stable base on which to develop without fear that bespoke applications will break every time something gets upgraded to the latest and greatest, but ultimately buggy version or the API changes breaking backwards compatibility.
So no, you will generally NOT find the very latest versions of various packages included in an Enterprise-class operating system such as CentOS. It's a feature not a deficiency.
Security patches and bug fixes are backported into the shipped version.
You'll have probably apps a little older (maybe often but not obligatory all the time) than on Ubuntu or Debian Testing for example (but if you use Fedora then no problem with this) but the stability will be excellent, and have you REALLY NEED of the "new" features in the newer version of apps?
The kernel, even if it is older by its version number (currently 2.6.18-128.4.1.el5), is very patched for support to more recent hardware (Red Hat is a big and recognized enterprise in the Linux world with many developpers, they make many hard work...) I have a Quad core with a Flash cards reader, DVD and BlueRay etc and there is no problem at all! And, like in some other distros (e.g Parsix, Debian), you can have something which does not exist in Ubuntu or Mint, I guess: a 32-bit kernel specially done for supporting more than 4 GB of RAM ("a version of the Linux kernel with support for up to 64GB of high memory. It requires a CPU with Physical Address Extensions (PAE). The non-PAE kernel can only address up to 4GB of memory. Install the kernel-PAE package if your machine has more than 4GB of memory.") Like that, and I use one, you can have the best of the two world: the large 32 bit library of softwares, codecs... (all are not in 64-bit) plus the use of all your RAM (usually in 32 bit the kernel supports 3,3 GB of RAM max, I guess) Great! And there is even a 3rd-party repo which "focuses on kmod driver packages to enhance hardware support (including filesystem, network, sound, webcam drivers)."
And like it's an Enterprise distro the support of every version is much longer than 6 months like in Ubuntu. Also they support the old versions. "Each CentOS version is supported for 7 years (by means of security updates). A new CentOS version is released every 2 years and each CentOS version is regularly updated (every 6 months) to support newer hardware. This results in a secure, low-maintenance, reliable, predictable and reproducible environment." For example:
CentOS 2 (2002-05-17/2004-05-14): CentOS-2 updates until May 31 2009
CentOS 3 (2003-10-23/2004-03-19): CentOS-3 updates until Oct 31, 2010
CentOS 4 (2005-02-14/2005-03-09): CentOS-4 updates until Feb 29, 2012
CentOS 5 (2007-03-14/2007-04-12): CentOS-5 updates until Mar 31, 2014
(the first date is for the release of RHEL, the second for the release of CentOS)
Of course it's the same thing for Scientific Linux.
In conclusion, RHEL5 and so its clones can be used like a desktop OS but you must accept some compromises... But we’re living in a world of compromises.
We can maybe consider them like the new XP, if you understand what I want to say... (for some explications, you can want to see here
, for the "new XP" idea, about the other views/opinions expressed in this blog post, it's not the topic/problem here)
Now, with all this information, it's up to you!
Maybe the best could be to test in multi-boot, right?
K.I.S.S. ===> "Keep It Simple, Stupid"
"Simplicity is the ultimate sophistication." (Leonardo da Vinci)
"Everything should be made as simple as possible, but no simpler." (Albert Einstein)