Used Instawallet once for a specific low amount transaction, no problems but it is a risk to never see your Btc again. I have the official client on my desktop and Electrum on my laptop. Electrum is a much better choice than Instawallet as has been already pointed out.
For now there are not many options for ASIC - Avalon are the only known company that actually managed to produce and ship them. Butterfly Labs is the other contender who are supposed to start shipping any time now but they initially had to ship their products in October or last year anyway...