The p1i by default comes with a rather drab theme, and the default ones are no good either. So, to spice up the phone’s look a bit, you can always download new themes(my current one is the PSP original theme from Themebin). While changing the theme is a no-brainer - just download (or beam) the theme(.utz) file to your memory card(or phone memory), use file manager to browse to the location where the theme is saved, click on it and just apply! The new theme - including wallpapers, sound schemes will all be applied. Most themes also come with icon replacements, which replace the original icons with new ones. To check if your theme has icon replacements, Just check if there’s a folder called “resource”, present in the skin archive. IF it’s there then your theme comes with an Icon pack.
For that we’ll have to do a bit of tweaking. No, don’t worry, it won’t cause you P1i to go berserk. First, connect your p1i to the computer via the USB cable(Bluetooth won’t do) in file transfer mode. Once the memory card is detected, browse to it. Just copy the “resource” folder from the theme folder over to your memory card. When asked to replace or overwrite, just say yes.
This is how my P1i looks, with the PSP original theme.