Hard drive swap or a new system?

[Microspeed]

Hi,
Presently I have a 1953-D6U. I have upgraded the ram and hard drive. It is still running XP. I have come across a 2623-D9U. I was considering swapping the hard drive and from one to the other. Among other things the GPU's are different and was wondering if the systems will boot ok and then all I have to do is run a system update to fix the driver issues? The alternative would be to reload the OS. The OS isn't really the big pain, it is iTunes. So I am just trying to avoid doing that, but I don't want any drama with the systems freezing and what not.
Eventually I wanted to upgrade the OS to Windows 7 on the 2623-D9U, so if a reload of the OS is really the only option, I would be doing that sooner than later. The other option would be to just sell them both and buy a T4xx and go from there.

I am looking for opinions.

Thanks