If u want to increase internal mem, use "Link2sd" app 4m d play store (root access req)
Install it and then using that, move apps tat u've installed into sd card. There r a few sys apps which r plain useless (these apps vary 4m region to region).. u can delete them BUT b4 doin so check if its alrite to del them -> there r some core services (eg: Android System) which, if deleted, could cause the phone to stop workin. u'd hav to flash d rom again (all ur non-backed-up data on phone would b erased)
the explorer has 150MB as internal mem, outa which around 50MB would be taken up by core sys apps.. d rest is urs!
i would suggest 1 thing.. except 4 widgets, move other apps (games etc) onto SD card. However, if any app has widgets associated with them, then u'd not be able to use those widgets if the app is on the card.