Upgrade 10D to 60D/7D or get a new L lens?

hello, i'd like to ask for opinions....

i invested in a 10D when it first was launched, along with a 28-135mm IS f/3.5-5.6 and 17-40mm f/4L. the next year, i splurged on the 28-70mm f/2.8L, and been using the 3 lenses since the next 2 years.

however, over time, as i started work, i never got as much time to shoot with my d-SLR as when i was a student, and i noticed i tended to use my compact digital cameras and lately my Panasonic GF-2 and iPhone for those quick snapshots/uploads, being easily to carry around.

but now that i've got more time, i decided to go back to serious photography and editing on my new fast PC.

i was advised by many dealers that i should upgrade my body as it's quite dated, and i would gain more from a faster/better new body. i also tend to like to shoot at the long end of my lens/pro-sumer cameras. i don't really have anything longer than a 135mm, so i'm thinking of getting the 70-200mm f/2.8L II.

i also remember the advice from many that good lenses will tend to hold their value, and as it stands, i think i wouldn't be able to sell or even get anything/much out of my 10D to a buyer. that's the main reason over the years of resisting my upgrade to a newer body, as i would like to get as much 'return' from my 10D, instead of just splurging in new bodies all the time.

however, do you think i'd get better/cleaner shots with a new 60D/7D and stick to my current lenses, or will the 70-200mm f/2.8L still give me great images on my 10D?

many thanks for your input.