Well, I got the new memory installed and all. Here are the new stats:

 $ free -h
             total       used       free     shared    buffers     cached
Mem:    3.8G      1.9G       1.9G    14M        91M        826M
-/+ buffers/cache:       1.0G       2.8G
Swap:         5.6G         0B       5.6G

top - 19:00:37 up  3:18,  2 users,  load average: 0.46, 0.51, 0.49
Tasks: 166 total,   2 running, 164 sleeping,   0 stopped,   0 zombie
%Cpu(s): 16.9 us,  7.6 sy,  2.3 ni, 71.1 id,  2.0 wa,  0.0 hi,  0.0 si,
 0.0 st
KiB Mem:   3982068 total,  2067916 used,  1914152 free,    94192 buffers
KiB Swap:  5855656 total,        0 used,  5855656 free.   850704 cached Mem

before free:
free -h
                   total       used       free            shared    buffers
  cached
Mem:          1.9G       1.4G       489M        18M        59M       535M

before top:
top - 22:16:50 up 1 day,  8:59,  2 users,  load average: 0.30, 0.19, 0.15
Tasks: 168 total,   2 running, 166 sleeping,   0 stopped,   0 zombie
%Cpu(s): 12.0 us,  2.3 sy,  0.0 ni, 84.1 id,  1.7 wa,  0.0 hi,  0.0 si,
 0.0 st
KiB Mem:   1983332 total,  1812836 used,   170496 free,    57184 buffers
KiB Swap:  5855656 total,    40496 used,  5815160 free.   560792 cached Mem
:-)~MIKE~(-: