Easily accomplished, but I don't recommend it as a first project to cut your teeth on. Better to know your key ingredients first. Break it all down into sections - building blocks - study each block before constructing the building.

Key ingredients for a simple temp logger:

1. PIC (16f628a, forget about the 84)
2. EEPROM (24LC256, PIC hasn't enough internal memory)
3. Temp sensor (LM335Z or better)
4. Power supply (Preferably regulated w/ adequate decoupling)
5. Serial interface for the PC (Max 232)

Five building blocks to study. Build & test each one before constructing the 5 story high rise. Same story applies for coding. Suggest getting blinky to work first before diving into a project like this. It's not terribly difficult but it is at 'novice intermediate level'

Trent Jackson