Advice R.E. D-Link 524 & VPN

I became disallusioned with LinkSys after my 2 yr old router (BFER41(?) 4
port) quit working. I had used a surge supressor with it, so lightning (via
power) was not the issue. (Red light was on and stayed on - could not reset
it, etc).
Since I was possibly going to need to occasionally use a wireless at home
for work related things, I saw a sale on a DI-524 and figured why not.
(just before the 624s went on sale )

I have hooked up all of my current network to the 4 ports on the new router.
Currently am not using the wireless.... set security to high on it... with
complex Key.

Anyway, whereas VPN used to be fast and not disruptivel with the LinkSys
router, and no external websites could be accessed on the VPNing machine,
NOW VPN is slow and I get some websites (and other home-network computers)
even while actively running Cisco VPN SW. This concerns me, because, at
least before, I had to shut down my firewall to run the VPN session
successfully. Interestingly, now I can keep Zone Alarm Pro Security Suite
active. That is a good thing, because I switched antivirus SW to the one
built into Zone Alarm, and when I'd shut down the firewall, it would expose
my system.

SO, my questions are:
1) Am I stuck with slow VPN sessions with the DI-524 (direct wired) or might
that be because it employs the encription (for Wireless security) to the
hard-wired ports too?
2) Does it sound like the computer is now more exposed during VPN sessions
if I were to shut down the firewall just before connecting the VPN session
(vs. when using the LinkSys router)?

I am not thrilled with the current performance of the DI-524 at present...
it does have the latest firmware.

Recommendations/ideas appreciated!
KWW