Hi antar
I presume you have a TravelMate 3043 laptop?
Firstly, you'll need to decide on which operating system you want to upgrade to. I'd avoid Vista (only because it is getting a little old now - plus it is resource hungry), but would recommend Windows 7 (because it is more like XP in operation). Windows 8 may be fine too, if it's what you want!
Secondly, you need to make sure that your machine can run a newer operating system, depending on the actual specification of your machine. So you'll need to run an "Upgrade Advisor" program:
Upgrade from XP to Vista
Windows 7 Upgrade Advisor
Windows 8.1 Upgrade FAQ's
It may be that there are no available drivers for your 3043 - check the Acer support site for your region to find out. Download them, and burn to disk for when you upgrade. There is also a possibility that your PC will need more RAM or even a BIOS upgrade.
Now, lets presume that your laptop passes the test for an upgrade. You'll then need to purchase a Windows disk. Either online or from a local PC store. Boot from the disk and follow all on screen instructions. When Windows has loaded, you may then need to use the driver disk you made earlier.
Finally, if all goes well, you will need to activate Windows (either online or by phone), then you're good to go!
If your 3043 fails the upgrade test, then the only option would be to install a Linux distro on it. I'd suggest Mint, which is light & almost like Windows in operation, or something like Ubuntu, which is popular, but different!
Hope this helps!
United States