Tomas -
The answer to your question has a lot to do with the student's expectations. We're in a similar situation, testing a LAMP 197 server which will get moved to the math dept just ahead of the autumn semester. We're currently at the end of an AT&T DSL connection - 3mbps down, 512k up; and to get a sense of what the server is capable of we hired almost 3 dozen Moodle familiar students (actually 35) and asked them to run through the 3 courses already on the server - we ask them to work against the courses anytime that was convenient, but asked them to especially try to be on btwn 7 and 9pm. The response has been quite positive. Since the school is a community college, there are no dorms, or importantly, students expecting or used to 100mbps or 1 gig bandwidth, ie, everyone accesses the brand A lms via the school's T-3 connection. The students that have been accessing our 197 have been commenting that they wish they'd have the same responsiveness with the school's server; for the 7-9pm accesses, the response time actually stays good (ie, 1-2 sec) as long as no-one is downloading a 5mb tutorial movie - then things slow down. The worse we've heard of is 30 secs to get a reply back. We've been pleasantly surprised. But in fact if one thinks about it: 500kbps is (approx) 50kbytes/sec, and when the average course page is 4-10kb and the average Moodle page is likewise (or less), subsecond response makes sense [locally here on a 100mbps network, 100ms responses are common]. The downside to this experiment is that: we hired the students hoping to load the server and see how it performed under at least moderate loads. So far we haven't seen anything resembling a load, ie, the single bottleneck by far has been the connection. [The server is much like what you're talking about: an asrock 785gxm mobo, 8gb ddr2-800 ram, amd 3.1ghz dualcore athlon, 3x raid-1 3gbs 250gb sata drives, driving Ubuntu 9.10 server, Apache2, and significantly 196MB allocated to APC, mysql with big buffers and memcached. So... in summary: the answer again, has to do with what your courses look like (bytes downloaded per page) and what your students expect in terms of response times. Personally, I'd give your setup a try, document what you see, and go from there.
hope that helps - greg
