I've needed to install PL/SQL Developer on a couple of machines lately. Unfortunately, it seems I only install this every few months. As this is a little more involved than the standard one-minute setup for most applications, I thought a blog might be appropriate. Here are the steps I followed.
1) Copy the Oracle 10g Windows 32-bit zip file from the Oracle folder on the I: drive to the C: drive. Extract it after copying to the C: drive.
2) Run the setup program. Select "Custom" for the install type and select everything. Yes, this is overkill, but it will ensure the proper folder structure into which the TNSNAMES file will be copied. For the install location, type "c:\orahome" or something equally simple.
3) Copy the appropriate TNSNAMES.ORA file into the folder c:\orahome\network\admin.
4) Reboot.
5) Copy the PL/SQL Developer installer to the C: drive.
6) Run the PL/SQL Developer installer and select the defaults.
7) Reboot.
8) Launch PL/SQL Developer. Choose AERO_SUNDOWN and complete the registration. Test things by opening one of your packages (edit spec and body).
