I think that is normal. My DX58SO does the same. If you want, time the events you see on the monitor and I'll do the same to confirm.
I just timed my start up from cold start. The results are:
steady cursor appears on black screen: 19 secs
flashing cursor begins: 32 secs
Win 7 Pro x64 starts: 47 secs
Desktop appears: 97 secs
Desktop completes loading: 135 secs
My system: DX58SO w/ i7-920 & 6GB memory.