OK then, a few thoughts...
i know i want to use raid 5 but thats only because that what everyone seems to use for servers. is there a better way?
AFAIK, RAID 5 is often used because it's a nice compromise between data security and
not sacrificing too much HDD space for that security. However,
RAID IS NOT A BACKUP.
If something goes wrong with your server (for example, several HDDs get fried at the same
time, which happened to me once due to a defective SATA controller), no amount of RAID
will protect your data (or at least you shouldn't rely on it to do so). RAID can give you
some added security and convenience, depending on your specific setup, but it's
not the be-all-end-all protective blanket for your data.
Also, depending on your needs, it is not always absolutely necessary to run a RAID 5 array
for a server, many people are perfectly happily running simple JBOD setups and it works
very well for them (and indeed for four HDDs such as in your case, this is not an unreasonable
suggestion IMO, I did that myself for many years and it did the job just fine).
The critical thing is that if the data on your server is important to you you should have
a separate backup anyway. I backup some stuff from my server, but not everything (not
worth the money, can afford to lose it).
Personally I'm running something similar to RAID 5, specifically ZFS with RAIDZ1 devices,
but I'm assuming since you're intending to run Windows that's not really an option here (if
you were willing to run something else: ZFS is awesome!

).
Anyway, sorry for the long essay: RAID 5 is not an unreasonable approach, but whether
or not there is "something better" as you say, depends on your needs, wishes and capabilities.
Regardless of RAID/JBOD I would definitely recommend having a good backup strategy, and if
you wanted you could run JBOD with four drives easily. As with most things, there are advantages
(some added protection, convenience in one single storage pool) and drawbacks (speed, as Tom
has mentioned, and you can't just chuck one drive into something else and use it on its own).
mobo i was thinking about a msi z77ma g45(matx), paired with the g2020 from my main rig when i upgrade. I have the atx version in my main rig and love it and the msi website says it supports raid 5 on the chipset.
That should work, I have the GD65 and am very happy with it. I haven't used onboard RAID
though, so I can't comment on that (see Tom's advice though).
i dont need loads of storage so i was thinking 4 x 2tb drives. is there a preferred option for hdds for server use? and a 60gb ssd boot drive.
I recommend looking at where the sweet spot is regarding price per GB at the moment and
then going with however many drives you think you need/want. Where I live that's currently
between 3 TB and 4 TB drives, depending on manufacturer and model, but $/GB aren't far
off for 2 TB models here, so you can easily go with that.
SSD for boot is a reasonable suggestion.
As for the drives themselves: As Tom says, it doesn't matter too much for home use. Define
what criteria are important to you (speed, low noise, physical form factor), look at what's
available and what it costs and then make a decision. I can recommend the WD Reds from
personal experience (not very fast, but reasonably quiet and decently priced), and Seagate
also make some low-rpm drives.
and finally which version of windows server should i get?
Haven't worked with Win in ages aside from the occasional office stuff, so can't comment
on that.