The front derailleur is friction only on a 6, 7, or 8 speed STI shifter set. If you are strapped for cash, stay with downtube shifters or stem shifters, as they are much more reliable and lower maintenance than any brifter model.

If you must spend money, upgrade the rear wheel to a 7-speed cassette model. You can get corn cob or stepped cassette. A couple of common ratios are 12-26 and 14-28. With cassettes you can mix and match the individual cogs by buying two or more cassettes that have the cogs you want and simply assembling a cassette.