I took out the 256MB Ram stick and have my desktop running off of a single 1GB RAM stick. This HP Pavillion a210n desktop PC is expandable out to 1GB only according to HP. So this leaves a spare slot for RAM.

Here is the question:
Is there any script etc I could change whereby I put in the 256MB RAM into slot 2 and expand the PC out to 1.256GB of RAM ORis the 1GB the full capacity I can go to??

Generally you cannot exceed what the motherboard was designed to handle. A firmware upgrade to the motherboard could be available which might make it possible to add more RAM. I said generally because I have owned 2 laptops and one desktop (all Sonys BTW) that stated maximum RAM but I was able to use more even without updating anything. It's a tough call on vendor built systems though. A lot of them don't want to allow for provisioning for overclocking or upgrading as it directly prevents them from selling you a faster, more capable system :)

I took out the 256MB Ram stick and have my desktop running off of a single 1GB RAM stick. This HP Pavillion a210n desktop PC is expandable out to 1GB only according to HP. So this leaves a spare slot for RAM.

Here is the question:
Is there any script etc I could change whereby I put in the 256MB RAM into slot 2 and expand the PC out to 1.256GB of RAM ORis the 1GB the full capacity I can go to??

Imo, it would probably pretend its not even there, it would largely depend on if any resources are allocated to that slot once the 1 gig is used up i would guess though, memory can be odd stuff.
As for the software solution, i honestly don't know im afraid mate, imo it would depend alot on if your comp can see it in the first place.

what stingx said i think mark, updating mobo bios, should tell you in the update notes.

regards,
jim.