I assume you are talking about the load average, not the uptime as your post might suggest (3.04 days to 4.5 days average would be kinda crappy
loadaverages generally come in a 3-column format. They give you the load average for 1,5, and 15 minutes. Load average is defined as the number of processes ready to consume a timeslice on the CPU at the time, plus the number of processes blocking on uninterruptible I/O.
This has several implications; one of which is that load average itself is not a perfect metric; the CPU may be idle and the load may be in the hundreds if a NFS volume dies or a disk is thrashing like there is no tomorrow. Conversely, the CPU may be pegged at 100% usage, but almost no I/O happening. (to figure out which is the case, vmstat and iostat can be used).
It also means that a "good" value can well depend on the number of CPUs or cores in the computer; on a fully loaded dual xeon with hyperthreading (=4 cores), a load of below 4 would indicate that the machine is idle at least some of the time, even with CPU-heavy processes. Most dreamhost machines have two cores. A CPU-heavy load average of 2 would indicate that the CPU is completely busy doing something (and anything below 2 is an underutilized machine). 4, if CPU-heavy, would mean that your server is rather busy, but it should still be responsive. If it's an I/O-heavy 4, the server might not be busy at all, just some people doing heavy I/O (which might not even be on your NFS server, so you'd be completely unaffected by that in any case). Once your load climbs to 6-10, I'd go ahead and contact dreamhost to have them investigate it, especially if you experience a sluggish server.
Load average alone is just a very rough indicator. If it's really high you know SOMEthing is wrong, but you can't really say what. Executing vmstat 1 (or vmstat 10 for better averages) will yield a bunch more information; happy manpage-reading