In answer to your question, which camera you should buy, either the Canon Powershot S30 or the Sony DSCP5 really depends on what you want your camera to do. Here is a spec list for both cameras. Hope this helps.
3.2 mp ccd 3.2 mp ccd
3x optical zoom 3x optical zoom
2x digital zoom 10x digital zoom
Lithion ion battery Lithion ion battery
Memory Stick (storage) Compact Flash (storage)
$999.99 plus tax $899.99
The reasons to buy the Canon are the following: Price, means of storage (more universal). If I had to choose between the two...I would pick the Canon. But just so you can keep your options open, the Kodak DX 3900, does all the Canon does + more for $559.90