Hardware performance and SQL

I'm a complete newbie to SQL and this forum etc. so please excuse if this is a stupid question:

I am running a SQL database on a HP DL360 G3 server, using the integrated 5i array controller and 2 15K disks running in RAID 0 configuration.

I've looked at some of the perf mon counters and see that it can peak with Disk writes/sec up to 150 or 200.
Questions:
is this a lot of writes/sec for this hardware?
how would I know how many writes/sec the hardware should be able to manage?
what sort of figures do any of you guys see?

Essentially, I want to see if the hardware is going to be up to spec for what we want it for, which are the best counters to monitor and what figures should I expect to see for what sort of hardware?

If anybody else is running any hardware similiar to this, I'd be interested to know what sort of figures you get.
I know the disks can handle 320MB/sec but the array controller is 160MB/sec, but would this be the limiting factor anyhow or am I just barking up the wrong tree :-)

Any advice would be appreciated.

Cheers Ian