Introduction to BGP

My company have two ISP connections but we only use 1 for all our traffic and the other was is for backup situation. We were planning to buy a netgear router (http://www.netgear.com.au/business/products/security/FVS336G.aspx#tab-features). There are two WAN port and it has load sharing capability. Are you saying that in the configuration we will not be able to set 80% to ISP 1 and 20% to ISP2 and it will be 50/50 distribution only? and if we do want to send 80% trafic through 1 ISP and 20% through another we don’t have an other option but to buy beefy routers to run BGP. Moreover, I heard that bgp is more about controlling incoming traffic flow from multiple ISPs to your network (you may be running multiple webserver in your network)rather than outgoing traffic from your network?