When to upgrade vs buy new bike

you will gain some benefit with "race" wheels, but don't expect miracles. it's a fairly high cost item, with relatively minimal improvements. but they look cool!

lots of threads in the past on how much benefit you actually get.

if you do invest in race wheels, consider how they would fit into a future bike upgrade picture.

I would agree that they are expensive in terms of Dollars/watt. But I wouldn't say that race wheels give you minimal improvements.

The wheels will probably make a bigger difference than moving from your "older bike" to a newer one.  While we all love a new bike, other than the potential for you to achieve a more aerodynamic position (which in some cases could be significant and, thus, worth considering), upgrading a bike should probably be the last thing on your list from a cost/benefit standpoint.

Wheels are generally very transferrable from bike-to-bike, but there are a few exceptions with some of the newer 'super bikes'.  I'd still strongly consider the aero front and disc cover solution for your current ride.

Don't forget good tires/tubes (e.g. GP4000S and Latex tubes), and possibly look into an aero helmet.

I think there is nothing wrong with an old bike.  If the bike fits well and you put the time in the saddle you can easily keep up with those on more expensive bikes.  A training partner of mine has a 2006 Cervelo Aluminmum frame and threw down a 2:34 bike time at B2B Half last year to win MC division.  That was without race wheels on a 6 year old bike.  He has thought about upgrading but has decided to keep the old bike and buy some race wheels instead.  I now have even less of a chance of beating him on the bike

edit: forgot he has an aero helmet too.