This may be a dumb question, but is there any benefit of using LAG on only one managed switch with 2 VLAN's? By default my switch, Netgear GS724T, assigns 8 LAG's to the default VLAN. I am using VLAN1 and a created VLAN20 that I am running a different subnet on each of these VLANs. Should I just disable the LAG's altogether? By the way all ports are untagged. Purpose here is to use one switch with two seperate subnets (192.168.1.x and 192.168.20.x).
Assuming you are talking about Link Aggregation Groups (please specify, because "LAG" can have many meanings), they only make sense when connecting two switches together, or two network ports on the same server, or in any other situation when you want to treat two physical links as a single logical one (this is known as "Etherchannel" in Cisco land).
This is useful for link aggregation, load balancing and failover; but it really doesn't make any sense if you only have one switch and you are only connecting single-NIC servers to it.