this is what I got ...
Hi! I finally was able to go shopping and this is what I got ...
(I will try to give details, in case this could be usefull for someone)
My pc:
HP PAVILLION t230.es as seen here:
http://h10032.www1.hp.com/ctg/Manual/bph08681.pdfSTEP 1
PREPARATION
I clean the main 160GB HDD leaving +120 GB free on it.
I check for errors in the HDD and I remove fragmentation. Everything is ok.
I unistall SL totally.
I reinstall SL last version (Second Life 1.13.3(58185) February 20, 2007)
I make some notes of ftp references in diverese areas to compare later.
STEP 2
MEMORY UPGRADE
PC has only 2 memory sockets, using 1 module of 512MB memory each socket.
I can´t upgrade memory from 1GB to 2GB. I need to buy two new 1 GB each memory modules.

I bought a blistered box containing 2 modules of 1 GB each of genuine Kingston memory. (174 euros / US$ 22

I replace the old memory modules for the new ones.
Pc takes the modules with no problem and it shows 2 GB RAM available in "My Pc".
I stress the pc opening multiple programs and it looks like the 2GB are real and they are really working.
I check SL and I compare:
- fps results: I don´t see any obvious increasing of the fps between "before" and "later" in the reference places I noted .
- sensasions: I don´t really appreciate any positive effect.
I don´t care this too much because I know having 2GB RAM is allways a good thing.
If I don´t take adventage of the 2GB in SL I will take adventage of them when using other programs for sure. No problem.
STEP 3
VGA UPGRADE
I went to my favorite megashop (maybe other shops are cheaper or more focused, but I like to do this way, sorry).
I was going to purchase NVIDIA 512MB XFX 7950GT (307 euros / US$ 402) that I previewed in the megashop's web.
The shopkeeper warns me about I will need PCI EXPRESS PORT to install that VGA so I have to change the plan.
I finally buy the only 512 MB videocard using AGP PORT they have for sale: A nicely boxed ATI RADEON SAPPHIRE X1600PRO AGP. (135 euros / US$ 177).
Following the recomendation from the shopkeeper I buy one 400 WATS POWER SUPPLY (15 euros / US$ 19) to replace my current 250 WATS POWER SUPPLY.
I remove the GEFORCE FX 5200 from my pc.
I install the new ATI X1600 in my pc.
I test my reference places to compare "before" and "later":
- fps results: I observe a very small increase of the fps.
In a reference place fps goes from 20-22 to 22-24. In another reference place (full club), from 2-8 to 4-10. And in everyplace I check more or less the 5%-15% gain.
- sensations: I feel some improvements. It's not what I was waiting for, but things work a little better with the new card I think.
Showing multiple buildings when flying over architecture rich areas works better. Open areas in general look like showing faster and smother.
CONCLUSION
In resume I feel rather disappointed, but oh well...
I´ve never seen a piece of entretainment software like this. Imho SL is totally above the industry standars with too insane hardware requirments.
Anyway I am fascinated for this proyect. I stay happy here more for what SL could be in future, than for what SL actually is (crashes, bugs, betas, new versions/patches every two days...)
I will take a break now. I promised myself not to open a pc in 3-4 moths (I really hate it).
I will buy a new system this summer, made it with all the top and newest parts of hardware available in the market the moment of the purchasing.
I guess I will abuse again of your generosity sharing your knowledge and I will ask for new advice in this forum, as you were so gentle this time.
Ill see how this potential wonder, SL, works in a modern top system then

Thanks to all who read and commented and sorry for my weird english.