Confused about install

For my Small Business Server 2003 ( running Exchange) with 4 clients, i just bought :

Order Summary:

ESET Smart Security 4 SBS Bundle w/RA 2yr 5-Users/Mboxes 1 ESET Smart Security 4 Business Edition, Client/Server/Messaging/MS Small Business Server Bundle, Incl RA, 2 year, 5-Users, Download Version - No Box Shipment. Free Technical Support

Then i receive two emails from ESET with usernames and passwords and downloads links:

DOWNLOAD
========
ESET NOD32 Antivirus for Microsoft Exchange:
<<http://download.eset.com/download/exchange/ndntenxs.exe>>


ESET Smart Security Business Edition for Microsoft Windows
2000/XP/2003/Vista/2008 (32-bit):
<http://download.eset.com/download/win/essbe/essbe_nt32_enu.msi>

ESET Smart Security Business Edition for Microsoft Windows
XP/2003/XP/Vista/2008 (64-bit):
<http://download.eset.com/download/win/essbe/essbe_nt64_enu.msi>

ESET Remote Administrator Console:
<http://download.eset.com/download/ra/era_console_nt32_enu.msi>

ESET Remote Administrator Server:
<http://download.eset.com/download/ra/era_server_nt32_enu.msi>

NOTE: Your .lic file is contained in the attached .zip file. Please
extract it before using.

I did download all the files (32-bit only) and.. I don't know how to start installation.

What should I install on sbs server ? ESET NOD32 Antivirus for Microsoft Exchange or ESET Smart Security Business Edition for Microsoft Windows
2000/XP/2003/Vista/2008 (32-bit) or both perhaps ( in which order) ?

Please help me.

thank You