I'm pretty sure buying would be the most effective thing to do in my case. My hardware isn't exactly great for heavy processing.
CPU: Intel Celeron 900 @ 2.2 GHz
GPU: Intel GMA 4500M
Buy coins or better buy some Ghash (contract miner)
Now i have 2Ghash contract and i gort about 0,01BTC per week.
New week a 25Ghash/s contrat will be started (i hope about 0.1BTC per week, depense on a difficulty)